DVD Shrink is slowing down, possible problem with CPU usage

I am having a problem with the time of burning. It used to take me 15 minutes to burn a dvd. The cpu usage was at 15-28% during the burn. It was normally at 0-4%. Now it is still normally at 0-4 but during a burn now it is at a constant 100% usage. It takes about 50 minutes to burn now. I have no idea why this is happening now. There is 42Gb free on my 60GB hard drive. And no other programs are runing at the time of burning. Please someone help me with this i need my 15 minute times back.