[js1138]

as each day goes by, the performance gets slower and slower.

I've seen that in a Gateway PC. It was fixed by reformatting and reinstalling the OS. I don't know what causes it but I have a theory based on experience with my sister's PC. It could be "soft" errors on the hard drive, causing multiple retries. the data is eventually read correctly, but performance tanks. You could get the disk manufacturer's repair program, which re-does the low-level format and maps out the bad spots, but in a professional setting, I'd replace the drive.

[Darksheare]

How about duplicate data that the beastie keeps looking at?
(Kinda like duplicate files under Windows 95... Windoze kinda liked to try and flip between the two.. making the system grind to a halt eventually.)