This problem can be caused by having another program running which uses the burner. You may not think there is another program active, but there is if you have the option of write / re-write on a disc -- using the DVD burner like another hard drive.
Win7 and Fujitsu Amilo desktop: I had trouble to burn. The burning process started but then the time went on and on and seemed to just stop. I executed the patch : "magix_burn_routines_2010_9.0.0.193_uk.exe" and now it works ok.