ive been having this problem with burning to my cd drive using Nero Ultra 6. i get the following error message:
Drive in use by another application

of course nothing else is running, i had this problem on my old comp after i installed windows xp pro but before when i used windows 98se i could burn...

I think the problem might have something to do with the windows XP's ability to burn files within the OS. When you put the CD in, does it take you to your cd burner drive? If so, just close that window and then open nero with nothing open. Should work ok.

i solved it awhile ago, just thought id post it:

go to start menu > control panel > services

find the imapi cd-burning COM service and go into its properties and disable it under the startup type drop down menu

:D