I'm getting this pretty much everytime I load up youtube... FF3 crashes on me.

running vista

Mate had that once, I just re-installed firefox.

what add ons do you have?

clear cache and restart firefox? i get youtube stopping after the first few seconds some times and that fixes it.

Reinstalled, cleared cookies+private data, no avail.

Addons:
Chatzilla
net usage
adblock (disabled for qgl ofc)
noscript
Downthemall

well I have those plugins and about 10x more and no lockups. when you re-installed did you actually uninstall it? Try deleting your profile dir, you'll have to re-enter all your private data if you have it stored and your bookmarks will vanish so back them both up and delete the dir holding your profile. Then re-download all your plugins incase one is corrupt and re-install flash player.

i get youtube stopping after the first few seconds some times and that fixes it.

yer, i get that too :(

reinstall/update flash?

I get it as well. IMO the problem is Flash player more than Firefox though.

IE runs perfect for me

Hmm, that happened on my vista machine as well a few weeks back. I just re-installed and it's been fine since.

i get it in chrome and firefox

arg... should i bother to comment... will my advice help...?

mate, basically i had this issue and i uninstalled the browser from the system and i removed a c:\windows\flash or something directory that held all the flash files for fireforx/chrome etc... then i re-installed and followed the usual links on the first flash page i went to to re-install the flash stuff and it started working normally again.

before that it was HELL random lockups, movies would play for 10-15s then stop/pause indefinatly...

mine is always plays the first 2 seconds and stops;