I have a seagate 80 gb sata, my problem is sometimes the system does not detect the disk, sometimes even if it gets detected, and when tested with seatool for dos, sometimes all tests get successful, some times the same drive fails on short dst(Disk self test), and when run with long DST, after 1 or 2 percent completion, all disk activity stops, and the system hangs, nothing happens without restart. Some times the disk goes to pio mode, uninstalling the ide controller driver fixes the problem. Sometimes i need to change the sata controller port to run properly, but problem also occur with the changed port. the disk was in warranty, and i got a new replacement drive, but the same problem started occuring with the new drive also. i suspect the sata controler(ie mobo) as well as hdd, i am equipped with a digital multimeter and a spare system. How can i detect the problem, the detection is problamatic becoz the faultyu behaviour is nondeterministic. Please help me out of this problem.