Hi, You can consider the [https://support.mozilla.org/en-US/kb/reset-firefox-easily-fix-most-problems Reset Firefox] feature via '''Help''' ('''Alt''' + '''H''') > '''Troubleshooting Information'''. (To revert to the previous profile you were using, close the new profile, start Firefox and choose the '''Default User''' profile. While the [https://support.mozilla.org/en-US/kb/profile-manager-create-and-remove-firefox-profiles Profile Manager] is open, you can also delete the newly reset profile (the one containing random numbers), or the former profile, as the case may be). [https://support.mozilla.org/en-US/kb/Managing-profiles Managing profiles] [https://support.mozilla.org/en-US/kb/Profiles?s=profile&r=2&e=sph&as=s Profiles Howto] The [http://ubuntuforums.org/ Ubuntu forum] would also be helpful.

Start Firefox in <u>[[Safe Mode|Safe Mode]]</u> to check if one of the extensions or if hardware acceleration is causing the problem (switch to the DEFAULT theme: Firefox/Tools > Add-ons > Appearance/Themes). *Don't make any changes on the Safe mode start window. *https://support.mozilla.org/kb/Safe+Mode *https://support.mozilla.org/kb/Troubleshooting+extensions+and+themes ---- Problems with bookmarks and history not working properly can be caused by a corrupted places.sqlite database file. *http://kb.mozillazine.org/Bookmarks_history_and_toolbar_buttons_not_working_-_Firefox *https://support.mozilla.org/kb/Bookmarks+not+saved#w_fix-the-bookmarks-file You can try to check and repair the places database with this extension: *https://addons.mozilla.org/firefox/addon/places-maintenance/