It could be the IDE controller if this was after swapping the cd drive. Almost all CRC errors are the result of the drive itself. However, burned cd's will tend to do this if it was poorly done, or incomplete downloads. Memory and cache can cause this as well, but that would be doubtful. It maybe that you have corrupted system files. Check eventvwr and see what it says. Also, you could (if you want to ensure its not cache) disable cache in the bios, but itll run slow as ****, and try swapping around memory (if you have 2 sticks, run with just one and then the other). May want to reinstall the MBD chipset drivers, as well.