Clear the cache and the cookies from sites that cause problems.

• "Clear the Cache": Tools > Options > Advanced > Network > Offline Storage (Cache): "Clear Now"
• "Remove the Cookies" from sites causing problems: Tools > Options > Privacy > Cookies: "Show Cookies"

Start Firefox in Diagnose Firefox issues using Troubleshoot Mode to check if one of the add-ons is causing the problem (switch to the DEFAULT theme: Tools > Add-ons > Appearance/Themes).

• Don't make any changes on the Safe mode start window.

• Troubleshoot extensions, themes and hardware acceleration issues to solve common Firefox problems

You can also try this page:

• https://www.google.com/accounts/ManageAccount

(repost) I tried a bunch of google hidden settings, re-install ff4, looked at ff error console, tried for hours looking for an answer on google, cleared cookies and caches, and this the only thing that worked for me: create a new firefox profile. I didn't even know that I had one to begin with. I had to re-install add-ons, import favorites, and re-sign to websites with passwords, which took me about 25 min. to get the bulk of it done.

http://support.mozilla.com/en-US/kb/Profiles

Now all things google work great (gmail, enter keys on search results, drop-down google header items, etc.), so it was completely worth the time to do it. Although it would have been nicer not to have to do it in the first place, but whatever, technology, sheesh, cry, moan, whine.....just don't leave me.