So basically trying to burn avi. files onto DVD and at first was fine but hasn't worked last few days. It still goes through the entire encoding process fine but when gets to actually burning onto the disc the disc ejects almost right away and the program ends without even an error message (disc remains blank). Would it have anything to do with CPU usage being near 100% or is something else wrong?
Save the project to your hard drive, and then manually burn using ImgBurn. Or, ditch Nero altogether and use something like DVD Flick.