Since the pointer was erratic, I suspected an interrupt problem. It turns out the drive had was now being accessed in
PIO mode. I tried the usual "switch to DMA" trick, but it didn't work! Fortunately, I ran into this forum posting over at CDRLabs.com where the third post detailed a procedure which seemed less scary than the first one and which worked, to boot!
Quick recap, in case that forum vanishes into thin bandwidth (hardy har har), because everybody knows all the forums eventually get pwn3d by spoiled twelve-year-olds-who-should-really-be-doing-their-homework-instead-of-saving-the-public-good-from-useful-information-and-loitering-on-my-damn-lawn:
- Open your registry to the key:
- Navigate under the sub-key
secondaryIDE channels, respectively), whichever one represents the channel for which your device isn't getting DMA-enabled
- Delete the value
SlaveIdDataChecksum, again depending on whether your DMA-deficient device is the
In conclusion, this momentary trip to the pre-DMA days really scared me and made me be thankful for DMA on this day of thanksgiving. I suspect one of my CDs was scratched or otherwise damaged and my operating system decided it was safer to switch to PIO mode.