Problem with both my CD and DVD drives

I have a Dell computer with which I am experiencing problems. I have a CD drive (D:) and a CD-RW/DVD drive (E:). I was trying to load new software the other day and I could not access either drive. I am using Windows XP. I restored my system to an earlier date (one which I knew the drives were working). This did not help the situation. I removed the upper and lower limits in the registry and rebooted and this did not help. I ran the PIOtoDMA executable from Windows. THis did not help. The computer recognizes both drives. In Device Manager, both drives are active and show that there is no problem. If I put a CD into the D: drive,it will act like it is reading it, but when I go to explorer and click on D:, it asks me to insert a disk into D:. If I put a disk into the E: drive, it acts like it is reading it. When I go to explorer and click on E:, it does not give me the message to put in a disk, but it does not show me the contents of the disk either. The only change to the computer since the last time the drives were working: I attempted to download a trial DVD burning software from KODAK. It downloaded, but was not successful when I tried to run the software. I restored to a date prior to when I attempted the download. Any assistance would be greatly appreciated!