Hi, You can update Firefox, with version 10 most add-ons are compatible, making the check unnecessary in many cases.

This might also be helpful: How to fix Firefox has just updated tab shows each time you start Firefox

Do you have the BitDefender toolbar in Firefox? Especially its version 2.0? Because this kind of issue may be related to BD Toolbar. If yes, remove it from your computer or upgrade BD.

It is possible that there is a problem with the file(s) that store the extensions registry.

Delete the files extensions.* (e.g. extensions.sqlite, extensions.ini, extensions.cache) and compatibility.ini in the Firefox profile folder to reset the extensions registry.

• https://support.mozilla.org/kb/Profiles

New files will be created when required.

See "Corrupt extension files":

• http://kb.mozillazine.org/Unable_to_install_themes_or_extensions
• https://support.mozilla.org/kb/Unable+to+install+add-ons

If you see disabled, not compatible, extensions in "Tools > Add-ons > Extensions" then click the Tools button at the left side of the Search Bar (or click the "Find Updates" button in older Firefox versions) to do a compatibility check or see if there is a compatibility update available.

See also:

• http://kb.mozillazine.org/Preferences_not_saved
• https://support.mozilla.org/kb/Preferences+are+not+saved