Start Firefox in Safe Mode to check if one of the extensions (Firefox/Tools > Add-ons > Extensions) or if hardware acceleration is causing the problem (switch to the DEFAULT theme: Firefox/Tools > Add-ons > Appearance).

• Do not click the Reset button on the Safe mode start window or otherwise make changes.

• 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.

You can check for problems with the places.sqlite database file in the Firefox Profile Folder.

• 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

Delicious Extension make this happen,try disable it. https://addons.mozilla.org/firefox/addon/delicious-extension/

Can anyone confirm if disabling this extension fixes the issue? We are seeing this in a few other places and it would help us to narrow down the root cause!

Looks like there is a bug already confirming delicious as the culprit. The addon is no longer being developed, so I'd suggest using sync!

Yes, that was the culprit in my case. Try adding the bookmarklet to your links toolbar instead of using the extension:

http://delicious.com/tools#title1

I did confirm that it is the Delicious Add-on that is causing the problem. Really kind of sucks and I don't like using sync because it is Firefox only.

It turns out they are still developing it. On http://www.facebook.com/delicious the Delicious team said to keep checking Facebook and Twitter since that's where they would announce it when the extension is updated.