There's no way this is an overheating issue. He says most of the discs he tries works. If it was overheating, he'd have reboots more often than just the occasional DVD rip. This is almost definantly either scratched discs/bad burner, or a windows problem.
You sound so sure of yourself.
Anyway, let me tell you a story about my friend who bought a Compaq laptop (Pentium III). He started having problems where the laptop would shutdown or reboot. It kept happening more and more and it finally trashed his WinXP. He was ready to throw the thing in the trash because it was out of warranty (so he thought), but I told him to let me take a look at it. It was weird because if I tried to reload WinXP from one of his two drives (DVD-ROM and a CD-RW) then it would reboot. I managed to get WinXP reinstalled and thought things were running ok until I used the other drive. Turns out that the drive worked fine, except that it was adjacent to the CPU and it's vibration had shaken the CPU's heatsink & fan too much.
Well, P3's had that auto-shutdown/lockup feature so they don't burn themselves up and essentially commit suicide. I did some more digging and apparently the mounting that Compaq had used was cheap and this happened to many users. We tried putting thermal paste to bridge any gaps and also tried to use epoxy to rebond the heatsink but it wouldn't cure. Since we kind of knew what the problem was now, he decided to get an estimate from CompUSA since they were the authorized Compaq repair center closest to him. Turns out that Compaq had extended his warranty by a year and they replaced the heatsink entirely.