Okay, so I’ve had this problem since yesterday after uninstalling some DVD writing programs…
I succesfully burnt a DVD-RW with ConvertxtoDVD, played fine on my DVD player which was a relief because I had a problem trying to find a program which worked!!
Then after removing other programs I had installed I tried the DVD in my drive and it wasn’t recognized, I then put in another DVD-RW of a different brand (which was previously recognized before) but it didn’t work! So I just presumed it was the DVD-R drive which wasn’t working. Then today I put in a DVD+R (blank) to burn and it wasn’t recognized either!!! But the DVD+RW which I burnt a movie on was recognized.
It doesn’t seem to be consistent in what kind of DVD is being recognized!!
I’ve done the registry fix and it hasn’t fixed it, I have uninstalled, then reinstalled my drive and still NOTHING!
Please can anyone help?? 
SONY DVD RW DRU-800A is what I have, I have even updated the firmware to see if that has been the problem but it hasn’t.
- Annie