Confirmed with Ubuntu 11.04 32-bit, using inkscape_0.48.1-2ubuntu2.
* Set Firefox as default browser, close any running instances of FF
* Start Inkscape, select Help->Inkscape manual
>> Firefox opens with Inkscape manual as expected
>> Inkscape displays persistent "'Inkscape Manual' working, please wait..." dialog.
>> Inkscape becomes unresponsive
>> Dialog cannot be closed by hitting "Cancel" button
>> Dialog closes, and Inkscape responds when FF is closed.
Confirmed with Ubuntu 11.04 32-bit, using inkscape_ 0.48.1- 2ubuntu2.
* Set Firefox as default browser, close any running instances of FF
* Start Inkscape, select Help->Inkscape manual
>> Firefox opens with Inkscape manual as expected
>> Inkscape displays persistent "'Inkscape Manual' working, please wait..." dialog.
>> Inkscape becomes unresponsive
>> Dialog cannot be closed by hitting "Cancel" button
>> Dialog closes, and Inkscape responds when FF is closed.