Recently I've gotten some errors relating to a particular hard drive. Like so:
Windows was unable to save all the data for the file [System Volume Information, $MFT, and similar windows places] The data has been lost. This error may be caused by a failure of your computer hardware or network connection. Please try to save this file elsewhere.
It was locking up my computer after it happened. I ran the ScanDisk/chkdsk XP equivalent error-checking tool. I ran a virus scan which seemed to pick up a few things. And, I swapped the power cable connected to the drive. After all this, the problem seemed to go away.
Today, similar issues have come back. The computer has even locked up on boot at the Windows log-in screen several times. I believe the computer is losing its connection to the drive somehow. Once, XP didn't even recognize the drive. I did notice before that the drive was not showing its name in the Device Manager. It just showed something generic like "Disk Drive". I currently have it unplugged so I can boot my machine without it locking up. Are these symptoms of a failing hard drive?
My other thought was that the PSU is failing or doesn't have enough power. Is this a possibility? The PSU is probably over six years old now. Most other parts have been swapped out at this point.
The drive is a 320GB Seagate Barracuda 7200.10 ST3320620A, and it's been working fine for about a year. I got a new CPU and had to replace the motherboard about six months ago.
Edit: I finally found another PSU to test with, and I'm pretty sure it isn't that now. I've found that I'm able to pick off a few files under linux before the drive stops working. It doesn't like to copy large or multiple files. Maybe a sign of bad sectors as has been mentioned in several answers already?