I Googled a number of sites this morning one of which was TechSpot. I had a problem with my DVDRW not working but it was recognized by Device Manager, so I right-clicked on the drive for Properties and saw that the driver was from Microsoft. I went on the Microsoft site and saw them promoting a new beta service, "Microsoft Fix It Online" for free, so I downloaded the program and it's one of the best diagnostic tools that I've seen. Amongst a list of things that it can do, the last item was CD/DVD problems. Clicking on it cleared whatever corrupt files were keeping me from using the drive and now it works like a charm again. 
