I'd like to reopen this bug with some of the additional information that you asked for.  Plus a note.  When i see this behavior (all the time now) and am using tabs, it seems that the page never completes loading (even though it appears to) as the spinner is still spinning on the tab. (even on this bug page).  Also Right Click on the page and "Back", "Forward","Reload" and "Stop" are greyed out, but all others are active.  These same buttons are greyed out in the top navigation.

This started happening to me this morning. I had upgraded the new linux headers last night, but see this with both -18 and -19, currently i'm in : Linux flipjeff 2.6.24-18-generic #1 SMP Wed May 28 20:27:26 UTC 2008 i686 GNU/Linux
Firefox is from repository and has been completely removed and reinstalled.

Please contact me with any other info you'd like (I did disable all add-ons and restart, but no difference)
Thanks
Jeff

Here is my find $HOME/.mozilla -name localstore.rdf
<?xml version="1.0"?>
<RDF:RDF xmlns:NC="http://home.netscape.com/NC-rdf#"
         xmlns:RDF="http://www.w3.org/1999/02/22-rdf-syntax-ns#">
  <RDF:Description RDF:about="chrome://browser/content/browser.xul#fbPanelBar1"
                   width="1406" />
  <RDF:Description RDF:about="chrome://browser/content/browser.xul#toolbar-menubar"
                   currentset="menubar-items,spring,throbber-box" />
  <RDF:Description RDF:about="chrome://mozapps/content/extensions/extensions.xul#extensionsManager"
                   width="520"
                   height="380"
                   sizemode="normal"
                   screenX="0"
                   screenY="25" />
  <RDF:Description RDF:about="chrome://browser/content/places/places.xul#placesContentKeyword"
                   ordinal="11" />
  <RDF:Description RDF:about="chrome://browser/content/browser.xul">
    <NC:persist RDF:resource="chrome://browser/content/browser.xul#main-window"/>
    <NC:persist RDF:resource="chrome://browser/content/browser.xul#sidebar-box"/>
    <NC:persist RDF:resource="chrome://browser/content/browser.xul#sidebar-title"/>
    <NC:persist RDF:resource="chrome://browser/content/browser.xul#stumbleupon"/>
    <NC:persist RDF:resource="chrome://browser/content/browser.xul#toolbar-menubar"/>
    <NC:persist RDF:resource="chrome://browser/content/browser.xul#nav-bar"/>
    <NC:persist RDF:resource="chrome://browser/content/browser.xul#PersonalToolbar"/>
    <NC:persist RDF:resource="chrome://browser/content/browser.xul#su_info_toolbar"/>
    <NC:persist RDF:resource="chrome://browser/content/browser.xul#fbPanelBar1"/>
    <NC:persist RDF:resource="chrome://browser/content/browser.xul#fbSidePanelDeck"/>
  </RDF:Description>
  <RDF:Description RDF:about="chrome://mozapps/content/extensions/extensions.xul#viewGroup"
                   last-selected="extensions" />
  <RDF:Description RDF:about="chrome://browser/content/browser.xul#nav-bar"
                   currentset="unified-back-forward-button,reload-button,stop-button,home-button,urlbar-container,search-container" />
  <RDF:Description RDF:about="chrome://mozapps/content/downloads/unknownContentType.xul">
    <NC:persist RDF:resource="chrome://mozapps/content/downloads/unknownContentType.xul#unknownContentType"/>
  </RDF:Description>
  <RDF:Description RDF:about="chrome://browser/content/places/places.xul#placesContentUrl"
                   ordinal="5"
                   width="569" />
  <RDF:Description RDF:about="place:folder=TOOLBAR&amp;excludeItems=1&amp;expandQueries=0"
                   NC:open="true" />
  <RDF:Description RDF:about="chrome://mozapps/content/extensions/extensions.xul#extensions-view"
                   selected="true"
                   last-selected="urn:mozilla:item:{AE93811A-5C9A-4d34-8462-F7B864FC4696}" />
  <RDF:Description RDF:about="chrome://global/content/customizeToolbar.xul#CustomizeToolbarWindow"
                   width="636"
                   height="400" />
  <RDF:Description RDF:about="chrome://browser/content/places/bookmarkProperties.xul">
    <NC:persist RDF:resource="chrome://browser/content/places/bookmarkProperties.xul#bookmarkproperties"/>
  </RDF:Description>
  <RDF:Description RDF:about="chrome://browser/content/preferences/preferences.xul">
    <NC:persist RDF:resource="chrome://browser/content/preferences/preferences.xul#BrowserPreferences"/>
  </RDF:Description>
  <RDF:Description RDF:about="chrome://browser/content/sanitize.xul">
    <NC:persist RDF:resource="chrome://browser/content/sanitize.xul#SanitizeDialog"/>
  </RDF:Description>
  <RDF:Description RDF:about="chrome://browser/content/sanitize.xul#SanitizeDialog"
                   screenX="599"
                   screenY="333" />
  <RDF:Description RDF:about="chrome://global/content/viewSource.xul#viewSource"
                   screenX="0"
                   screenY="25"
                   height="737"
                   width="1529"
                   sizemode="maximized" />
  <RDF:Description RDF:about="chrome://mozapps/content/extensions/extensions.xul">
    <NC:persist RDF:resource="chrome://mozapps/content/extensions/extensions.xul#search-view"/>
    <NC:persist RDF:resource="chrome://mozapps/content/extensions/extensions.xul#viewGroup"/>
    <NC:persist RDF:resource="chrome://mozapps/content/extensions/extensions.xul#extensionsManager"/>
    <NC:persist RDF:resource="chrome://mozapps/content/extensions/extensions.xul#searchbox"/>
    <NC:persist RDF:resource="chrome://mozapps/content/extensions/extensions.xul#extensions-view"/>
  </RDF:Description>
  <RDF:Description RDF:about="place:folder=61&amp;excludeItems=1&amp;excludeQueries=1&amp;excludeReadOnlyFolders=1"
                   NC:open="true" />
  <RDF:Description RDF:about="chrome://browser/content/places/places.xul#places"
                   screenX="0"
                   screenY="25"
                   height="500"
                   sizemode="normal"
                   width="1408" />
  <RDF:Description RDF:about="chrome://global/content/customizeToolbar.xul">
    <NC:persist RDF:resource="chrome://global/content/customizeToolbar.xul#CustomizeToolbarWindow"/>
  </RDF:Description>
  <RDF:Description RDF:about="chrome://browser/content/places/places.xul">
    <NC:persist RDF:resource="chrome://browser/content/places/places.xul#placesContentTags"/>
    <NC:persist RDF:resource="chrome://browser/content/places/places.xul#placesContentUrl"/>
    <NC:persist RDF:resource="chrome://browser/content/places/places.xul#placesContentDate"/>
    <NC:persist RDF:resource="chrome://browser/content/places/places.xul#placesContentVisitCount"/>
    <NC:persist RDF:resource="chrome://browser/content/places/places.xul#placesContentKeyword"/>
    <NC:persist RDF:resource="chrome://browser/content/places/places.xul#placesContentDescription"/>
    <NC:persist RDF:resource="chrome://browser/content/places/places.xul#placesContentDateAdded"/>
    <NC:persist RDF:resource="chrome://browser/content/places/places.xul#placesContentLastModified"/>
    <NC:persist RDF:resource="chrome://browser/content/places/places.xul#places"/>
    <NC:persist RDF:resource="chrome://browser/content/places/places.xul#placesContentTitle"/>
  </RDF:Description>
  <RDF:Description RDF:about="chrome://firebug/content/firebug.xul#firebug"
                   screenX="500"
                   screenY="312"
                   width="901"
                   height="551" />
  <RDF:Description RDF:about="place:folder=BOOKMARKS_MENU&amp;excludeItems=1&amp;excludeQueries=1&amp;excludeReadOnlyFolders=1"
                   NC:open="true" />
  <RDF:Description RDF:about="chrome://browser/content/places/places.xul#placesContentDateAdded"
                   ordinal="15" />
  <RDF:Description RDF:about="chrome://browser/content/places/places.xul#placesContentTags"
                   ordinal="3"
                   width="194" />
  <RDF:Description RDF:about="chrome://firebug/content/firebug.xul">
    <NC:persist RDF:resource="chrome://firebug/content/firebug.xul#firebug"/>
  </RDF:Description>
  <RDF:Description RDF:about="chrome://browser/content/places/places.xul#placesContentVisitCount"
                   ordinal="9" />
  <RDF:Description RDF:about="chrome://browser/content/browser.xul#stumbleupon"
                   currentset="su_toolbaritem"
                   hidden=""
                   collapsed="true" />
  <RDF:Description RDF:about="chrome://global/content/viewSource.xul">
    <NC:persist RDF:resource="chrome://global/content/viewSource.xul#viewSource"/>
  </RDF:Description>
  <RDF:Description RDF:about="chrome://browser/content/preferences/preferences.xul#BrowserPreferences"
                   screenX="519"
                   screenY="248"
                   lastSelected="paneTabs" />
  <RDF:Description RDF:about="chrome://mozapps/content/extensions/extensions.xul#searchbox"
                   value="firebug" />
  <RDF:Description RDF:about="chrome://browser/content/places/places.xul#placesContentDate"
                   ordinal="7"
                   hidden="false"
                   width="19" />
  <RDF:Description RDF:about="chrome://browser/content/places/bookmarkProperties.xul#bookmarkproperties"
                   screenX="149"
                   screenY="167"
                   width="401" />
  <RDF:Description RDF:about="chrome://mozapps/content/downloads/downloads.xul#downloadManager"
                   width="485"
                   sizemode="normal"
                   height="332"
                   screenX="0"
                   screenY="25" />
  <RDF:Description RDF:about="chrome://mozapps/content/downloads/downloads.xul">
    <NC:persist RDF:resource="chrome://mozapps/content/downloads/downloads.xul#downloadManager"/>
  </RDF:Description>
  <RDF:Description RDF:about="place:folder=BOOKMARKS_MENU&amp;excludeItems=1&amp;expandQueries=0"
                   NC:open="true" />
  <RDF:Description RDF:about="chrome://browser/content/places/places.xul#placesContentDescription"
                   ordinal="13" />
  <RDF:Description RDF:about="chrome://mozapps/content/extensions/extensions.xul#search-view"
                   last-selected="urn:mozilla:addons:search:https://addons.mozilla.org/downloads/file/30423/firebug-1.2.0b3-fx.xpi" />
  <RDF:Description RDF:about="chrome://browser/content/preferences/permissions.xul">
    <NC:persist RDF:resource="chrome://browser/content/preferences/permissions.xul#PermissionsDialog"/>
  </RDF:Description>
  <RDF:Description RDF:about="chrome://browser/content/browser.xul#main-window"
                   screenX="0"
                   screenY="25"
                   width="1590"
                   height="945"
                   sizemode="maximized" />
  <RDF:Description RDF:about="chrome://browser/content/browser.xul#fbSidePanelDeck"
                   width="186" />
  <RDF:Description RDF:about="chrome://browser/content/browser.xul#PersonalToolbar"
                   currentset="su_toggle,personal-bookmarks" />
  <RDF:Description RDF:about="chrome://browser/content/preferences/permissions.xul#PermissionsDialog"
                   screenX="559"
                   screenY="306"
                   width="481"
                   height="411" />
  <RDF:Description RDF:about="chrome://browser/content/places/places.xul#placesContentLastModified"
                   ordinal="17" />
  <RDF:Description RDF:about="chrome://browser/content/browser.xul#su_info_toolbar"
                   currentset="__empty" />
  <RDF:Description RDF:about="chrome://pippki/content/exceptionDialog.xul">
    <NC:persist RDF:resource="chrome://pippki/content/exceptionDialog.xul#exceptiondialog"/>
  </RDF:Description>
  <RDF:Description RDF:about="chrome://pippki/content/exceptionDialog.xul#exceptiondialog"
                   screenX="549"
                   screenY="234"
                   width="501"
                   height="480" />
  <RDF:Description RDF:about="chrome://mozapps/content/downloads/unknownContentType.xul#unknownContentType"
                   screenX="612"
                   screenY="315" />
  <RDF:Description RDF:about="chrome://browser/content/places/places.xul#placesContentTitle"
                   width="414" />
</RDF:RDF>