Apollogies for stealing your thread but i have a similar problem that was not solved by the same advice. I dropped my laptop a while back and the damned thing stopped working, anyhows took out the HDD and hooked it up to my tower (the tower is very old but working) when i attach both the working HDD that was in there already and the laptop HDD the BIOS refuses to recognise either saying "primary master failed, primary slave failed" I've checed the jumper switches for both and they are set correctly, plus they are on the correct ATA connector on the wire. What else should i check/ why is it doing this???
Cheers, F