Comment 3 for bug 512787

This has also happened to me several times .

The small snapshot of the tab window being moved hangs and remains.
The cursor remains stuck as grabbing-hand-and-arrow. It moves around,
but there is no effect if I try to click on something whether it is Firefox-related or not (the hints seem to work, though).

Ubuntu has not crashed, as I can cntrl-alt-F2 and use the login terminal (although sometimes there is a long delay after I enter my password, before giving me the prompt).
I filed ubuntu-bug from this Terminal. I copied down the website address of the bug that was reported by hand, as I was unaware of how to select-cut-copy from the Terminal (or perhaps write it to a file somehow...). I apparently wrote it down correctly...

I have recovered each time by using htop to identify the principal Firefox process, and using F9->SIGKILL to remove it.
cntrl-alt-F7 then returns me to a Firefox-less completely operable Ubuntu desktop.
I then restart Firefox, of course.

I'm not sure why this comes up as "Firefox 3.5", as I recently upgraded to 3.6.8. I did see 3.6.8 in the report as well, but...