First off, the drive is a 2.5 year old Western Digital 250gb PATA drive (slave) in a WinXP Pro desktop. I use it to store all of my media: Pics, music, and video. About three months ago, I noticed when I would save new music or pics to the drive, sometimes the files would be corrupted. Not corrupted in the normal "it won't open" way; The would be garbled. Pics would have lines running through them or be cut off half way through. Music would play like it was on a scratched CD. Also, file/folder seek time was really slow. Also to note: The drive wasn't making any funny sounds.
At first, I though this was due to the files being corrupt before I downloaded them. But, if I downloaded the same exact file off of the same site onto my system drive, it would be fine. So, I did what any intelligent person would do: I ran Windows ScanDisk and Defrag. After that was finished, almost all of the files were gone! I immediately rebooted the machine, and on start up, scandisk found a ton of "orphaned" files, which led me to believe that the FAT tables had been corrupt. When the machine started back up, all of my old files were back. The drive seek times greatly improved. New pics and music downloaded didn't have the aforementioned issues.
I thought something might still be amiss, so I downloaded a utility called DiskCheckup which analyzes the SMART information. In my experience, SMART isn't always the best at determining imminent failure, but gives a good baseline for drive health. When I ran the scan, though, all parameters came up as good. In fact, such important variables as "bad sectors" and "overheat" all came up as zero. This perplexed me even more.
About a week ago, the original problem began happening again. In my eyes, this drive is no longer reliable. Could this be an I/O error?
I'm an IT professional and I've dealt with many hard drive errors, both at home and at work, in the past, but I've never ever heard of this happening before. I've already chalked this drive up as bad and I'm going to backup and replace it, but I'd like to understand what exactly is happening here. Any ideas?