You can google the old CODE 39 issue as well as TweakUI that let you hide drive letters.
Bios shows that the dvd drives exist. Select any hard drive in Windows Explorer; right click, select Hardware tab. It lists the dvd drives along with all hard drives. But Windows Explorer can't find them; nor can Windows Media Player, nor Nero nor any other Windows program.
Everything was working fine .. playing and burning cds and dvds ... then the two DVD drives just disapeared!
The drive trays open and close but no program can find them. Using Start/Run H: (the drive letter for one dvd drive) gets "location is unavailable".
If I unplug the ribbon cable, they disappear from BIOS but reappear when ribbon cable is replaced.
Is it possible to HIDE dvd drives from Windows?

Chowhound
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GameFAQs
GameSpot
Giant Bomb
TechRepublic