System Freeze from HSF driver

I am running 64 bit ubuntu 7.10 on an intel core 2 duo with 2gb ram.
I've tried the 7.60 oem driver and the 7.68 free version but both will
connect to the internet and then after a while, from 1 minute to
twenty my system will freeze and I'll have to hold the power button. I
can't restart X or even go to virtual terminals. It seems to
completely lock the keyboard since the caps lock light won't even go
on and off. This doesn't happen if I'm not on the internet, on wifi,
or on ethernet so I know its the modem and not an application.

Thanks,
Brandon