I think you may want to try creating a new profile and see if the new profile makes a difference.

Profile Manager - Create, remove or switch Firefox profiles is where you can find help with creating an new profile.

The crash reports I found didn't help much. They all look like this:

https://crash-stats.mozilla.com/report/index/cd3b3e1e-bf76-4935-88f6-1ebcf2120301 Firefox 10.0.2 Crash Report [@ ffi_call ]

You said the problem still happens when you restart in Firefox Diagnose Firefox issues using Troubleshoot Mode, then "Continue in Safe Mode"? In that case I would look at Roboform, since it's caused many crashes in the past. See http://kb.mozillazine.org/Firefox_crashes#Roboform

I just took a look at the Comments tab in one of your crash reports:

https://crash-stats.mozilla.com/report/index/187d0501-8092-447f-bd8a-3c1a72120301 Firefox 10.0.2 Crash Report [@ ffi_call ] 

... and there are lots of comments about the crashes starting after installing a new version of RoboForm. Check it out yourself!

Thanks, all. I fully expected it had something to do with Roboform. Roboform has sent the problem to their developers. They are apparently taking it seriously. I asked for and got a link (http://www.oldapps.com/roboform.php) to be able to reinstall Roboform 7.7.2. I installed it and FF seems stable for now!

Thanks for reporting this. I added the information about RoboForm 7.7.3 to http://kb.mozillazine.org/Firefox_crashes#Roboform and referenced this thread.

I see RoboForm 7.7.4 is now available at http://www.roboform.com/download so you could try that version to see if the crash problem has been fixed.

Thanks, Alice. Their help desk sent me the link yesterday. I installed 7.7.4 and it is stable! Success!