Well … assuming your burner is on the Secondary IDE Channel (ie. not on the same IDE channel as your O/S harddrive), you can try uninstalling the Secondary IDE Channel. Reboot, and XP should reinstall it and hopefully set it to DMA.
Other things could be as simple as the cable connection. Maybe try reseating the cable. If (by the off chance) the cable is attached upside-down (very unlikely) or backwards, I’ve heard it can affect performance.
I know some drives recommend using 80-wire cable (vs. 40). Not sure how relevant this is to your drive.
Btw … (assuming this is a PIO vs DMA issue) … this person might be a good resource for this issue or for BTC burners in general:
http://club.cdfreaks.com/showthread.php?t=90055
Also … since I’m not familiar with Dynex burners … we are talking about an internal burner, yes? If this is external, there may be a host of other issues involved.
Some helpful tips from womble:
http://wombleintheuk.tripod.com/Final/DMA/DMAXP.HTM
If none of this works … then, you’ll need to consult the more experienced users in the BTC threads. You can start by doing an advanced search for keywords such as “PIO mode”, “DMA mode”, etc. specifically in the Optical Drives / BTC section.
Good luck!