I was having horrible crashing issues with the 32-bit version of Firefox 3.5.1 on my Fedora Core x86_64 system, especially while using Flash, but also while doing simple tasks like printing. Fedora Core (unlike Ubuntu) can run both 32-bit and 64-bit binaries on the same setup, due to /lib being 32-bit, and /lib64 being 64-bit.
I finally realized that maybe the issue was some bizarre and missing 32-bit library that the .tar.gz distribution of Firefox was relying on, and not giving me a reasonable error message about a missing dependency.
So, I did a:
sudo yum install firefox.i386
which indeed pulled in a bunch of dependencies that I think had been cleaned up by some other process that looked for orphaned dependencies.
Although I’m not using the Fedora-provided version of Firefox 2.0, my personal install of 32-bit Firefox 3.5.1 (with Adobe flash, 32-bit) is now back to its prior “reasonably stable” point.
I’m still planning on doing a fresh install of Ubuntu 9.04 when my new hard drives come in.