I have a Dell Dimension 4700 with two drives. They are shown as DVD Drive D and CD-RW Drive E..  Until recently I could insert a music CD in Drive D and it would start playing immediately.  Now nothing happens upon insertion in Drive D.  I tried to start play through the My Computer icon and clicking the Drive D icon.  I get a message to insert a disk in Drive D even though one is in that drive.  The CD will play in Drive E using that method to start it.

I will appreciate any help in this matter.