Well, I haven't disconnected the other optical drive, but I have tried just about anything else. I have stopped all the background programs that might influence the burning, and I removed a virtual CD-ROM that I think is a leftover from an old installation - but still no go.
The problem is that I have to start a burn to see if it worked - so now I am 3 hours into a 5 hour burn..

I am using the embedded burning engine in the program - and it might be thats the one that is slowing things down, but I have been unsuccessfully with the imgburn and Nero engines. I use imgburn for DVD5 and it works fine, its the Dual layers that is the problem..
Anyway. I will try the imbgurn next time, and see what happens. The media is so damn expensive here, so I don't want to wast any more money, but on the other hand - I would like to use my compute for other stuff than burning too

Thanks for trying to help me out!