Over time, you will accumulate errors during hard disk reads
and writes. (It's a statistical fact.)

If I recall correctly, Microsoft set a threshhold for the 
number of errors it would tolerate before renegotiating its 
IDE drivers. You go from ATA133 to 100 and so forth.

I think it might even go below ATA 33 into the PIO modes.
Anyway, the simplest resolution to this is to go to your
system hardware, and remove your IDE controller. Windows will 
reinstall the drivers upon a reboot and should perform the 
same as it did before.

(Assuming your files aren't fragmented, your registry isn't a mess, etc...) 

If this was useful, or you have a question, let me know.   [ more ]