Windows 7 - Windows 7 x64 and a Fujitsu Magneto Optical unit

Hi,
I have one Fujitsu MCJ3230SS SCSI internal magneto optical unit connected to an Adaptec 29160 (PCI-X).
The SCSI controller board is configured correctly and the Magneto Optical unit is recognized and correctly appears while browsing in "Computer".
The first time I've installed it (previously it was installed in a different PC with Windows XP professional and worked perfectly) in my new computer, I've made several backups of my important data.
A few days ago I needed to restore one file so I took one of the backup disks, inserted it into the unit but it keeps asking me to "insert a disk" when I try to browse the disk, also with different disks.
Strangely the icon of the unit now appears "grayed".
I tried to restore default controller settings with the Adaptec built-in utility (you can run it by pressing CTRL+A at boot) but eventough the Fujitsu unit is detected, Windows 7 keeps drawing it "grayed", as if it were disabled.
I tried also another SCSI fujitsu unit but the result is the same.
Does somebody here have experience with those kind of units and Windows 7 x64?
What kind of problem may be it?

Regards,

Roberto