That would be because your an idiot and more than likely dont have DMA enabled on all your ATAPI devices, mainly your CDR.

Right click `My Computer', click on manage go down to device manager click the little plus hoobie on IDE ATA/ATAPI controllers, right click on Primary IDE Channel. From there go under Advanced Settings and set the transfer mode to `DMA if available' on all IDE devices you have on that controller, repeat this process on your Secondary IDE Channel.