812@832 Reading Problem

I am having a problem with my Liteon 812@832. All of a sudden it cannot read movies. it can write them, but when a retail dvd is placed in the drive, the drive ac ts like nothing has been inserted. When loading up DVD Decrypter, it says Medium Not Present. When I load a burned disk in the drive, it can read it and DVD decrypter sees it is a burned movie, but I still cannot view it or open it via My Computer… Any Idea what the problem could be? i tried updating to latest FW, uninstalling the ide channel, the drive itself. Even tried a system restore, and nothign seems to be working. it is set for DMA. Any assistance would be great. Thanks