Since it is past warranty, remove the drive from that FU case (I had one, too) and install it as an internal drive. I did that with mine--using it right now, because of the floods--and the drive works great.
Anyway, this will tell you what the problem is. I and others have found that the simple-sht drive has always been a problem: PC doesn't recognize it, always have to turn it off and then on when it spins down, etc. Let us know what happens.