Constant crashing with FF13 and newest Flash. Tried reinstall of previous version; nothing but trouble

Question

A few weeks ago, everything worked very nicely on my desktop computer. Then I succumbed to the nagging and "upgraded" to FF13, as well as the new Flash and Real players. Immediately, FF started crashing. First, it would instantly crash with any tab that had Flash embedded.
OK, I disabled and then finally uninstalled Flash and Real, but that didn't solve the problem; it would still crash 3 or 4 times a day, and with as few as 30 tabs open (the previous version could easily run 100+ tabs). Apart from those 3 "updates", the only other thing I had done was to update my existing plug-ins and add-ons, but I even tried disabling all of my plug-ins and add-ons; FF still kept crashing!
Today, I got fed up and uninstalled FF13 (after using MozBackup), and d/loaded and installed the previous version of FF. Did that solve the problem? Nope. Now, I can't get Tab Mix Plus to work, nor can I find my hundreds of old saved Sessions with Session Manager.
I tried uninstalling Tab Mix Plus and then reinstalling it, but I just get an error message saying it couldn't be installed. In fact, this is the THIRD time I've had to type this post, since the first time, I mistakenly tried to open a new tab to search Tab Mix Plus in Google, but the f{ck1ng tab opened Google right over this page, wiping out my almost finished post, and the second time, I went to Tools-->Options-->Manage Add-Ons-->Tab Mix Plus-->Options, and it froze up FF, requiring restarting it! Indeed, it seems as if the entire Manage Add-Ons menu is now buggy and generally freezes up.
I am *this*far*away* from ditching FF entirely (after 7 years of being loyal to it) and trying Chrome. It really is infuriating how difficult it is to get this straightened out! Any help would be greatly appreciated.

Answer 1

Have you tried creating a new Firefox profile and testing whether that will run without crashes? This is a non-destructive test that creates a new settings folder. It picks up plugins from the registry, but otherwise looks like a fresh install.
If you haven't used the Profile Manager before, this article describes how to start up into it and create a new profile: [[Use the Profile Manager to create and remove Firefox profiles]].
You can import your bookmarks by restoring a backup from your previous profile folder. For convenience of access, make a copy of your last bookmarks backup on the desktop. You can find that folder using Help > Troubleshooting Information > Show Folder; navigate up one level to view your last active profile, then into the bookmarkbackups folder. Copy the latest .json file to the desktop. Then in the dialog pictured in the article "[[Back up your bookmarks or move them to another computer]]", use Restore > Choose File to import that file into your new profile.
Can you get through a day without crashing?