I think I have a bad power supply in my desktop, because if I try and burn a dvd or play a game on it. It will just shut down like if you pulled the plug. At first I thought it was a virus so I reloaded windows on it but that did not work. Whats od is after it shuts off a few times it will work fine most of the time.

Have you checked the temps? And the Fans also. Sounds like the fans are sluggish and are eventually freeing themselves to do the job of the cooling. Look inside and see if there is any accumulated dust on the fans. And look at the PSU cooling fan also and see if it is functioning as it should.
Open the case and see if that has any effect. Could be the HDD and DVD rom throwing off a lot of heat - maybe.

Have you checked the temps? And the Fans also. Sounds like the fans are sluggish and are eventually freeing themselves to do the job of the cooling. Look inside and see if there is any accumulated dust on the fans. And look at the PSU cooling fan also and see if it is functioning as it should.
Open the case and see if that has any effect. Could be the HDD and DVD rom throwing off a lot of heat - maybe.

I did that and to the touch the power supply is not hot. Oh and my cpu is runing at 36c under load.

It could be a memory problem. Check that the memory cards are seated in the slots. Games and ripping are both memory intensive. And run Memtest

http://www.memtest86.com/%3Ehttp://www.memtest86.com/

Also check all other cables and their connections while you are in the box.