I thought you might like to know what I found when I had this issue and spent a number of hours finding the cause.
I bought a pair of Corsair 2GB sticks for the same motherboard and of course tried to run them in dual channel mode. I found the system would randomly freeze with the same symptoms you are having.
Eventually, after a number of driver changes/updates, I ran memory tests using memtest86 in dual channel mode and it would hang after a few minutes. Running the same tests in single channel mode resulted in no errors.
I'd suggest try running in single channel mode, but I'm not sure whether it's the motherboard or the memory that is at fault. I decided to just leave it in single channel mode.