Windows has two modes of talking to IDE devices, PIO mode and DMA mode. DMA (Direct Memory Access) mode is far faster and more CPU efficient, however it automatically gets disabled after a certain number of errors as a fallback position to take on a drive that can’t do DMA or a bad cable. The problem is CD drives often encounter errors simply due to the nature of the medium, and if you are anything like me and buy packs of 150 DVD’s for $25 off ebay then you will know probably have experienced this pain.
To find out what mode they are using go to Start->Control Panel->System->Device Manager. Look for IDE ATA/ATAPI controllers and expand that then look at the Properties for Primary IDE Channel and Secondary IDE Channel. If any devices are listed as PIO mode then you are suffering from this problem.
To fix it download the script from this page which should fix you right up.