DVDs & CDs do not load

My NV52 has stopped recognising that there are DVDs or CDs in the DVD drive. When I try to insert a disc I get a message to "Please insert a disc into drive D", then the drive ejects the disc. Same problem/message when I start the computer with a disc in the D drive and then try to check on the disc using Windows Navigator. I have tried using the troubleshooter w/ success and I have checked the status of the DVD drive and the computer shows that it is working normally and the software is up to date (2006). I even cleaned the lens on the drive without success.