I've had this before with some badly-behaved video editing software. This registry key:
Code:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Class\{4D36E965-E325-11CE-BFC1-08002BE10318}
has two values in it, something like UpperFilter and LowerFilter, which are how third-party software hooks into the generic CD and DVD drivers. If you have anything installed that is hooking in, renaming them to something out of the way will temporarily disable the hooks and let Windows work with the drive free of any tampering. Reboot for it to take effect. It's a shot in the dark, but it might work for you.