Naguall,
I would double-check that thought that it used to work in DMA mode for several reasons:
1) CD-ROM drives (or any optical device for that matter) doesn't use a "driver" per se. Instead, it has onboard firmware that Windows reads. When you check Device Manager, it shows you a generic driver is installed, but it is really using the drive's firmware. Therefore, it shouldn't really matter if you change PC's. Both read the device info directly from the drive.
2) If you're so certain, put it back into the other PC as a test. Make sure the DMA setting sticks and that there are no errors.
3) The version of Windows might make a difference regarding how compatible it is with DMA mode on certain drives. Check to make sure both PC's that the drive has been in have the same version.
You also might want to try changing the IDE cable. Sometimes a 40-wire is required on older drives to get the right speed, even though 80-wire is backwards compatible. And if you already do have a 40-wire, then do the opposite and replace it with an 80-wire.
There are many, many possibilities here...
~cdogg
"Insanity: doing the same thing over and over again and expecting different results." - Albert Einstein
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