Running it fine here, no crashes at all - however, I may be able to help you.
I was going to point you in the direction of a guide to making sure you survive a Firefox 0.9 upgrade, but I can't find it now :-)
Here goes:
You need to back up two things before the upgrade. Your firefox profile and the firefox profile settings. If you didn't set up your firefox profile manually before (as in, you ran the Firefox 0.8 installer and just starting using Firefox straight away), then you only need to back up one location.
This location depends on the machine and on the version of Firebird/fox. On Windows 2k/XP:
C:\Documents and Settings\username\Application Data\Firebird
OR
C:\Documents and Settings\username\Application Data\Firefox
is a dir that needs to be backed up.
On Win9x, if you're not using multiple Windows profiles:
C:\WINDOWS\Application Data\Firebird (or fox)
I would then advise deleting the original directory after you have backed it up.
Then uninstall Firefox 0.8 and delete the directory it was installed into.
Then start the 0.9 installer, which should give you a perfectly stable browser and new profile.
You can definitely copy the following files out of your old Firefox profile and into the same relative location in your new one:
bookmarks.html (your bookmarks data)
You should be able to copy the following files -==-:
cookies.txt
user.js (if you use one)
I would advise trying to port as little of the Firefox profile as you need. My parents' install of Firefox had stability issues when I tried to 'be clever' copying too much over.
Reminder: Firefox is not deemed "everyone friendly" yet, that milestone is meant to be when it gets to and past the v1.0 release.