Looks like time to go to chrome.

I have the same problem - if I attempt to compose mail or open my settings it hangs and then calendar, web, documents, etc stop working but if I open one of them before attempting to compose they work fine. Composing then hangs and breaks them.

Chrome works fine.

I followed tiltwithquixote's solution and it worked for me too

I went to Tools-->Clear recent history, and cleared everything except site preferences. gmail works fine now.

Note I cleared for the time range of the past hour...

I just got the same problem since Firefox had updates for version 3.6.6.A accepted the updates and now gmail is not working. The page loads.I can see my mail fo a few seconds and it goes to the agenda page.This way I cannot open any of the messages or even compose one. I suppose it isn't a problem with gmail cause it goes fine with the internet explorer and google chrome. What should I do to solve this. I've praised firefox to everybody and now we have this. I hope someone is able to help me.

Same problem here.

Windows XP Home, firefox 3.6

anytime I use gmail or facebook, pretty much every other website that refreshes itself, firefox magically disappears on me. So annoying!!!

They know about the problem. Why don't they address it then?

i can get to gmail but everything displays very poorly. guess i should go back to safari...

Opening in my FF 3.6.6 causes loading the inbox and seconds afterwards the calendar opens. that sucks! I can't even read any mails in Firefox, have to use safari instead. Rollback to 3.5.10 and deleting cache did not solve the problem in any way...

Really irritating

HELP..Firefox is making me CRAZY. It has been locking up on Gmail and in Gmail chat as well as in this window. It also locks up when trying to post comments on Facebook. I uninstalled 3.6 and went back to 3.5.11 to no avail. I don't know what changed but it has rendered Firefox unusable as far as I am concerned. This is my work machine and the IT person has also tried working with it. I have upgraded IE to the latest version but I don't like it. PLEASE give me some ideas people. Thank you!!! Oh and worth noting is the fact that when I am in Firefox and it is working ok the task monitor shows one instance of the application running. When it locks up, the task monitor shows two (but there is no other window open. See screenshot.

I'm using Firefox 4.0b13 pre on Linux Mint and I'm having this sad problem, don't want to use Chrome to check Gmail!

Upgraded to Firefox 4 yesterday 23rd March. Gmail no longer working properly. Emails selected by check boxes not recognized when actions selected, Delete, Archive etc. etc. Message 'No conversations selected' Emails appear to be 'greyed out' but check boxes show ticks when clicked. Have checked in IE 9.0.8080.16413, no problems at all with Gmail. Please, please, don't make me go back to IE !

Problem resolved!

Uninstall Firefox 4, re-install Firefox 3.6.13

Simple, elegant, satisfying!

Chrispy that's not a solution for me, I have to test my clients websites in the latest browsers... firefox 4 will not let me use gmail effectively.

Also, Diqcus commenting modules on my clients sites don't work full either. Yet on different computers they work fine (even with firefox 4).

I'm on Windows 7 64bit and I'm using firefox 4 latest, reinstalled recently from the firefox website with no effect.

Firefox is even crashing when I try to download the another version of it. I've had to download it from another computer and move it across.

This is infuriating!

Running Firefox 4.0 Final here and the check marks + actions are not working for me as well.. I have tried safe mode to rule out adblock or any extensions from being the source of the problem. Works fine on another computer.. I have tried re-installing and clearing my cookies.

I was having problems with FF crashing frequently when I had version 3.6.6. I would get the plugin container extension error message when it crashed.

Last week, I upgraded to FF 4 and now gmail doesn't display properly at all. More often than not, I have to reload several times before it does display correctly -- and it takes FOREVER to load.

I was having an issue where part of gmail would load, then i'd get an alert with no text and no ability to close it, whether i clicked cancel or accept.

All I had to do was clear my cache:

Preferences -> Advanced Tab -> Network sub tab -> "Clear Now" button under "offline storage".

cleared it up for me. didn't even need to restart gmail.

(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.