That sucks. Strange, too, Seagate and Samsung are both pretty good drives....Do you still have the same power supply, logic board, etc? It might be a power supply or IDE controller sending spikes that the drives just can't take for very long. Either way, that blows. Try smacking it [hard] with something like a screwdriver handle right when you put power to it...every now and then that gets it working, but usually only when the spindle motor stops. Sometimes it works for that too. Good luck.

Later.