Yes the MP7040A supports over-burning. It can also burn to 80M CD-Rs. It could also be the brand of CD-R media that you're using. I use Acer, Memorex, and Smart & Friendly 80M CD-R's. Ahead has a listing of all compatible drives and which features they support. What program are you using to burn CD-R's with? Not only must the drive support over-burning, but so must the CD-R burning software. Do you have the 1.40 firmware for your MP7040A? I do recommend disabling DMA for the CD-RW drive and I would use the following setup.
Primary Master = Hard Drive
Primary Slave = Hard Drive
Secondary Master = CD-ROM Drive
Secondary Slave = CD-RW Drive
[This message has been edited by Best4x4 (edited 05-18-2000).]