NEC 4571A problems

I just bought a NEC 4571A and i have a problem with it. It reads cds very slow like 750kb/s. It starts with a stable 3000+kb/s and then after a min it drops to 700+kb/s. When it works ok the green light blinks but when it starts going slower the light is allways.

And is DMA mode activated?

Oh and it reads DVDs ok with 10000+kb/s data transfer and i figured out something wierd all my cds that were burned with my TEAC W540E (cd burner) have this problem but those that were burned using my other TEAC W512G ( combo burner) have no problems :confused: The wierd thing is that both TEACs read the files with no problems and another SONY DVD drive has no problems with cds burned by my older TEAC W540E.

Cant find DMA is it in Control panel/system

Control panel, system, hardware, device manager, IDE ATA/ATAPI controllers, primary/secondary controller (or something like that)