That's fantastic - I reset the DMA button, and I managed to burn the disc I had failed to burn on the weekend. If this has fixed up the problem, I'm ecstatic. I should've asked you guys ages ago, instead of soldiering on and getting nowhere month after month.

According to Nero CD-DVD speed, my MID is TTH02 and the firmware is 0A3.

I checked my hard drives under Device Manager.
On both channels the Transfer Mode was "DMA if available".
On the Primary IDE Channel the transfer mode was Ultra DMA Mode 5, and on the Secondary IDE Channel the transfer mode was Ultra DMA Mode 2.

maineman, you mentioned getting a firmware update. Is that something I should be doing? (Leader is just a local computer manufacturer.)

Thanks again to both of you
eaziersed