NEED HDD HELP ASAP

A few minutes ago my HDD disappeared from Windows Explorer. It is a WD 1TB Black HDD that is a few months old. After restart it reappeared. After reboot, I checked event viewer and there were some errors. It said disk disappeared from the network without first being prepared for removal. I'm worried by HDD may be dying. Has anyone else had this problem before? My HDD with the OS hasn't disconnected so I don't think it's a motherboard issue. I'm running a virus scan to see if I have any problems. Hopefully it won't stress the HDD too much. Also, I checked the SMART status with SpeedFAN and the drive appears to being doing well. Help Please!

The HDD is detected after a restart. So it can't be a connection issue with the Sata or power cords.

Run the hard drive in another computer. If possible also get a different SATA and run in your computer.

Basically you need to do a little troubleshooting. I'd be very surprised if it was the hard drive.

You need to prove it's not problems with:
1) motherboard
2) hard drive
3) power or data connections
4) Windows

This following probably won't solve the issue but it won't hurt. I've done it on many computers that have mysterious hard drive issues.

1) Open up the Device Manager
2) Right-click and Remove all SATA controllers (just remove them all)
3) Reboot and WAIT for controllers (and then drives) to be reinstalled

*There's a common glitch that affects XP/Vista and Windows 7 where the Read and/or Write performance oddly drops very low for a hard drive. Doing the above has fixed the problem every single time.

I just looked up Event ID 51 on Microsoft's website it states

"In this case, no harmful affects are experienced. For example, event ID 51 is logged when blank media such as CDR, CDRW, DVDR, and so on, is inserted into a writable drive while a USB device is plugged in. The system logs the event even though the disc is writable, and the USB device is still usable. In these particular cases, you can safely ignore the log entries, and no additional action is required."

I have a USB flash drive plugged in, but not a blank disk, just my DVD of WIC.

That was for the warning.

There Error was a Event ID 12

After reading some things, maybe it isn't a problem with my HDD and hopefully MB, because my other HDD has never done this. It is a 3 year old WD 320GB AAKS HDD.

Any other ideas?

You're absolutely right. I switched the SATA cable to my boot drive and it didn't load OS. My PC said load boot drive and restart. I got rid of the cable and used a new one and it works great. SMART says all HDDs are fine. Thanks again.