Crrrrrashing

[JoeNightmare]

Ok, so this has been happening for a while and i've been ok with it but i just crashed while fighting a bear and it scared me to death, i lived though.
I log in perfectly ok, i play perfectly ok, but every now and then my game freezes up for like 10 minutes, it takes 0 cpu during all this time, and then it force logs me off. and if it doesn't force logs me off then i just freezes till i quit and restart it.
I use an ATI radeon, 1 gig of ram, and a duel core processor. Any ideas?