I have an XPS 400.   A  problem has materialized recently, and I don't know how to rectify it.

If I boot with a disk in either the CD or DVD drive, I can then get to the contents of the disk, but if I insert the disc while the computer is running, I cannot get it to even tell me anything is in the drive by clicking on the logo in "My Computer".  If I double click the drive logo, the little hourglass appears next to the cursor and try as I may, I can't then get anything to happen.  If I opt out of  "My Computer", the screen will return to my desktop, but  there are no logos on the desktop, only the background.  Not even the "start" button nor the toolbar.  The only way I can get out of this predicament is to push the handy ol' manual  "stop" button and cold boot.   Can someone provide me with a clue how to fix this problem?

Thanks.     Jackster