Problem with my Hard Drive and its partitions

I am having a strange problem. I have two hard drives with 80 GB each. Drive 1 has a 10 GB windows partition while drive 2 is divided into two 40 GB partitions. Whenever I try to copy any data, the computer restarts and windows is no longer there. Sometimes the partition will also get wiped. First I thought this might be due hard drive so I changed the hard drive.
But nothing happened so I changed my motherboard and it worked. Nothing happened for a few months. Then last week, as I turned on my computer, my 2nd The hard drive was completely blank. I formatted it and tried to boot up but it failed as windows were absent. Any help ?
