this is a serious step, but try reinstalling a fresh OS copy. if you don't wanna lose the current setting, load the new copy as a dual boot option. and then reinstall windvd and try playing the DVD. If it still doesn't, it is definitely a hardware issue.
BTW, before all this, you might wanna see if the drive is able to read the DVD by browsing to windows explorer. If you are able to copy files on the DVD to the hard drive, then there is hope. if not, i'd doubt if the fresh OS install would give you and good results.
We are frustrated. The DVD player on our Compaq 2100 has stopped working. We were using Intervideo WinDVD 4, and all of a sudden, now it won't play. When the DVD is inserted, it makes a sound--a light grinding, then a click, then a light grinding, then a click. It never engages and we can't use it to play DVDs. The drive is the same for CDs, which play just fine, and it's also a CD burner, and that feature works fine. Which tells me it's probably not a hardware issue? I re-installed all of the drivers just to make sure that wasn't the problem and nothing changed. I also installed WinDVD 7, just to see if that would help, but nothing. Still grind grind, click.
Any hints or suggestions?