This could be several things;
Is the drive appearing in Device Manager properly, with no notifications?
Have there been any changes to the hardware or software config recently?
One thing to definitely check is the availability of firmware updates for the drive via the manufacturers web site (Driver updates as well)-- another is to use Dell support and look at any updates available for your service code (labeled on the back or side of the machine).  Barring that, try using Nero utilities to find and test the drive.  If the drive can read a cd, then it is likely a software error. If the drive is completely dead (can't read or write) check connections and try a hardware re-install.  
Bruce Waugh
Information Technology Instructor
Craven  Community College

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