I have Firefox version 3.6.6 now installed and running smoothly. Hopefully the same for others that have bitten the bullet and installed it. If not running better, please read this thread carefully to help try to smooth out the bumps.
Going to the Mozilla Firefox website, you can read more about the 3.6.6 update there.
That's good news. It's looking more and more like the last FF update was a bit of a disaster for flash (lol) Thanks for letting us know 3.6.6. seems to be OK.