CD Reads But Won't Play - Disappears

Dell 755 dual core 1.8, 3 gig ram. I installed Window 7 on the machine, updated the drivers for sound ect. The problems is the CD drive, it can see it read what�s on the disk, when you try to open it, it disappears completely off the machine, it goes out of devise manager, reboot it comes back. If i try to play a music CD it loads the WMP and tries to play you can see it playing, the track bar moves but no sound comes. If I play the in-build music or play the video it plays and I hear the music. I've changed the drive letter as someone suggested still the same. At one point I had my 3g modem in that show up as the CD drive. It must a conflict somewhere, where I dont know. Set it to both 32 & 64 bit configurations its the same on both