Windows Vista - Missing CD/DVD-Rom drive
Apparently it seems that this is an age old fix for even XP systems. If you venture to the registry key above by doing the following steps:
Click on the start menu.
If this is a Vista machine in the search box type in "regedit" without the quotation marks.
Maximize the HKLM and then go ahead and browse until you reach the key listed above.
In the right panel you'll see something along the lines of "UpperFilter" and "LowerFilter" you want to click on each "filter" key and hit delete. Click yes when it asks to confirm if you wish to delete the key.
Let me know if this works.