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

See Troubleshoot extensions, themes and hardware acceleration issues to solve common Firefox problems and Troubleshoot issues with plugins like Flash or Java to fix common Firefox problems

You can also check http://kb.mozillazine.org/Locked_or_damaged_places.sqlite

Thanks but that didn't help so add-ons and themes don't seem to be the problem.

The problem goes away if you revert to Firefox 3.6.9 so it looks like it's something amiss in version 3.6.11

I can't go back to 3.6.10 as the file won't download.

I've now tried installing v3.6.12 but the problem is still there so have gone back to 3.6.9 again. Isn't anything being done about this?

Same problem on both of my Mac's. Rolled back to 3.6.9 and it's all good. Also tried the beta and had the same problem. Sure looks like an issue with 3.6.11

Hi, I had a similar problem mine was solved by telling my FIREWALL system that firefox was allowed to acess the net.

Firefox v3.6.12 was hanging when searching the left Window pane for bookmarks. Rolled back to 3.6.9 and that fixed the problem. Just updated today to 3.6.13 and it still hangs, STILL BROKEN. Rolling back to 3.6.9 again.

Current Firefox versions use SQLite version 3.7.1 and there have been issues reported with that SQLite version.

Bug 595530 - Searching bookmarks and history is much slower after SQLite 3.7.x upgrade

(please do not comment in bug reports)

I just updated to 3.6.15, problem still exists. Can't believe this hasn't been fixed yet? Hangs for about 30 seconds while trying to search for bookmarks. May roll back to 3.6.9 yet again!!!

The problem is still there for me too with v3.6.15. When is something going to be done about this? I've rolled back to 3.6.9 - again.