Having a Bit of a Hard SATA Time.

For the past week I've been having some really weird things happen to my PC. All of a sudden one of my 1 Terrabyte Seagate HDD's started doing a Houdini on me. I'd be downloading something to it and all of a sudden the download would stop and the system would come to a muddy downshift of speed. Not good. I can defrag the drive, I can search and open files within it and even move files around within the drive itself. What I can't do is move anything into it because it 'runs away'. I thought that it could possibly be my computer memory because I kept getting a memory error message whenever I'd close Windows Explorer but that all checked out fine. I tried disconnecting different drives, including that one, in case it was a power consumption issue but that was good too. I finally got fed up and rebooted and restored to the last known good configuration and it came right up again. I figure that I must have disturbed the registry somewhere and altered a RAID control command or something, even though I don't use a RAID setup. I just use the two 1 Ter HDD's for storage only. We'll see what we shall see.