Sounds like the RAM to me, i get a similar thing happen when i clock the ram too high. I have to re-set the Cmos to get it working again. Maybe you could borrow a stick from your brothers computer?
Thanks to BradleyKZN for polishing my sig
“oooooooooooh fire!!! and girls...GIRLS and fire!!!!!!! oooooooooooooh *runz around clapping hands together*” -Marineborn