First of all, the advice to install Beta7 was bad advice, as it is a beta-release, not a final version of Firefox, and, thus, quite subject to myriad problems. In addition, if you installed Beta7 and used your existing Firefox profile, then that profile (which may well have been faulty before the Beta7 installation,) is very likely to be ruined.
Given my assumption about reuse of an existing profile, then I can only offer this advice. It will take some time, but I believe you need to do the following steps to try to eliminate the existing problem(s):
1.Start the Firefox Profile Manager and create a new profile:
Profile Manager - MozillaZine Knowledge Base
2. Close the Profile Manager; close and remove Firefox.
3. Download and install a copy of Firefox 3.6.12, the most-recent release version. When the install process is finished, do not start Firefox, then close the installation process.
3. Restart the Profile Manager, select the new profile, start Firefox. This should fix the crash manager process--unless, of course, you have some other, and quite unknown problem on your computer.
If the crash manager problem is still there, then at least you will likely have reduced the number of Firefox-related items that might be causing the problem; that, in turn, should make it at least somewhat easier to then figure out and fix any underlying problems.
4. If, alas, the problem remains, then I suggest that you follow this procedure:
a. With Firefox running, in the URL bar, type about:crashes ; this will give you a list of the crash reports you have submitted.
b. Copy two or three of the report ids, then post them in a new thread on
Index page • mozillaZine Forums , in the Firefox Support forum; this does not require that you register for MozillaZine, and will allow some people who actually have some understanding of crash reports to look at yours to see if they can identify the cause(s).
Again, I suggest that you first follow the advice above in this missive, so that any new crash reports will be from the use of a release version of Firefox, using a new, clean profile. This should help eliminate any extraneous causes of the problem(s) caused by the use of Bet7 and/or an older, possibly corrupt, profile.