My ol' Western Digital 160GB HDD has switched from DMA to PIO mode twice in the last three days (I naturally switched it back). I suppose this could be a sign it is dying, or is Windows XP being a bit flaky and resetting the driver?
Hmmm.... it seems to have just switched again to PIO mode this very moment. I'm noticing a lag simply when transferring a 1GB file to another hard drive. The window is estimating transfer time to be 20 minutes, even FireFox is showing a bit of lag.
it was happening to me about an year back or so, i just changed my IDE cable and the problem was resolved..
There can be 2 reasons for such a switch:
1. fault in the cable (IDE/SATA/Power cable) connection, or also when these cables become loose overtime (i had PATA hdd that time, so my loose power connector was causing the problem in another pc)
2. hdd fault
So, first try replacing the cables, i hope that works for you