Try slowing the burn down.
Try another drive if you can. Drives sometimes go bad.
While I have had one drive go bad on me (out of probably 50 that I've owned), I find that it is far more common for the cabling on the drive to go bad, particularly with old Parallel IDE cabling (the flat, ribbon cables). These are extremely prone to failure, and I've had more than one failed cable drive me nuts until stumbling on the solution.
SATA cables are now far more robust, but the connectors are still fairly prone to failure.
So... The moral of the story is, if you think you might have a bad optical drive, try replacing the IDE cable first! If you're still on Windows XP, also checking to make sure Windows hasn't turned off DMA access and restricted the drive to PIO mode is also always a good idea, as that'll cause burning problems galore:
http://sniptools.com/vault/getting-back-to-dma-mode-in-windows-xp