Comment 2 for bug 650973

Thank you for your bug report. I have been trying to reproduce the bug, but as you wrote it cannot be easily reproduced. Firefox bugs are often caused by plugins, themes etc. so I would ask you to please create a new and clean firefox profile as described here
https://wiki.ubuntu.com/MozillaTeam/Bugs#Try%20with%20a%20new%20profile
Be sure not to delete your current profile.
Should the error occur again, please also attach the .xsession-errors file (located in your home directory),
Thank you!