Why is my PC not burning CDs at all?

Hey everybody,

So, my PC is not burning at all, and its pretty annoying,
It all started when i went to burn a dvd, and nero would not even start the burning process when it said burning failed,
i thought okay its a nero problem, then i go to burn a cd when i get some sort of error like 'incd(or something like that).exe has encountered an unknown error and needs to close, and blah blah blah.
So i booted up my xp cd and had setup repair the xp installation, then i go to burn a dvd with nero, and im thinking its working, then i look and the dvd is empty, then i tried another burning program, winAVI, same thing, then ConvertXtoDVD, same deal,
What could be causing this?

Sorry this isnt very specific,
if you need it i will provide more details later,
Thanks,
Tanner.