Hard drive missing in windows xp?

[Epic]

I have 3 hard drives. The other day I was unpacking a .RAR file in my E drive and for some reason my computer just shut off, almost like there was a short. I opened it up checked all of my connections and looked for possible ground out points and found nothing, so I rebooted and the E drive was missing. The bios detected it but windows did not. I rebooted again and it was back, so I figured everything was fine. This morning I booted up my computer and again the E drive was missing I rebooted it was back but as a matter of fact as I write this question it just disappeared again. help.
It is not showing up in the device manager.

 

[Williamw]

Without further details or looking at it, my guess is the the drive assigned to 'E:' is failing. My advice is to back-up anything important on it and replace it. The unexpected shut-down also indicates that something drawing power is amiss.