I am suddenly having this problem with not being able to reply/forward to (certain Gmail conversations) - for some conversations the tabs operate normally. Now using, Mac OS 10.5.8 and experienced the presence of this issue with Firefox 3.6.10. AND 3.6.13 but not with Beta 4. I have used Safari and the error is not reproducible. This issue is exclusively present to Gmail in FF 3.6.10. / 3.6.13. I can confirm that FF config is presently dom.storage.enabled. I have started FF in safemode, disabled, updated and enabled all plugins and add-ons, restarted FF and desktop many times, the issue is still present in FF 3.6.10/3.6.13. Only some conversations cause this error. When I click on particular conversations reply/forward tab, the page freezes and the only way to temporarily resolve this, is to click the refresh icon as F5 will not work. It does not freeze the whole FF browser, just the window with Gmail. I need a fix as FF is my primary browser. Thanks in advance! :-)