I have a 2 or 3 year old Lite-on DVD RW SHW-1635S. I also have AnyDVD and CloneDVD.
All was fine until about mid last year when the player started to be able to read and write fewer and fewer DVDs. Today I fed it 4 DVDs and it could not read any. (Explorer does not show any to be present).
OK so I downloaded and installed the latest firmware from Lite-on and it can read 2 DVDs but not the other 2. The firm ware is dated Mar 2006.