If it's Windows 7 that is normal.
The drive doesn't show until a disc is inserted.
You must have some magical drives. That's not normal on any windows 7 PC that I've seen.
Does the drive show in the BIOS? If yes, try running this Fixit scan.http://support.microsoft.com/gp/cd_dvd_drive_problems
If that doesn't help, delete your upper and lower filters.http://support.microsoft.com/kb/982116