Ok, so far, we've moved the burner to a new system.
Aspi has been checked.
Different software has been used.
Different media used.
Mobo with different chipset + IDE has been used.
Moved burner to different IDE chain, and hence different ata cords.
Dma is on/off.
Used cd's on different standalone + PC players.
Not recording from Sound card.
Assuming that the source files have been checked and are OK.
Assuming that since multiple programs have been used to convert MP3 ->wav to put onto cd's, and those wav files are OK (no artifacts).
Did you uninstall the aspi layer before installing it.
Do you have any packet writing softwares installed (eg:InCD).
Have you ever installed and adaptec/Roxio burning software? :Z
Have you tried changing the power supply?
Have you definately removed/disabled all unnecessary equipment. I've had a similar problem introduced by the following equipment
PCI Network card.
PCI TV tuner.
The problem was mainly that two devices which didn't like sharing particular IRQ's were sharing IRQ's.
Can you try disabling ACPI and then manually assigning IRQ's to the devices?