Optical drive absent

Hi to all.
Acer Aspire 7220. Vista installed. DVD-RW gets current, opens, is alighted.
When I insert aCD I can hear it spin (as customary), but nothing happens.
No show in either My Computer or in Device Manager. Have checked in
Regedit, Local Machine,System, CurrentControlSet,Control,Class, 4D36E965-
E325-11CEE-BFC1-08002BE10318 : No Upper filters, No Lower filters ! Only
what follows:
DriverDate REG_SZ 6-21-2006
DriverDateData REG_BINARY 00 80 8c a3 c5 94 c6 01
DriverDesc REG_SZ CD-ROM device
DriverVersion REG_SZ 6.0.6002.18005
InfPath REG_SZ cdrom.inf
InfSection REG_SZ cdrom_install
MatchingDeviceId REG_SZ gencdrom
ProviderName RG_SZ Microsoft.

I first thought of bad connection, faulty cable and the like,,,But the device
works OK. I even took it out and replaced it with a guaranteed workingdevice.
Nothing. Microsoft "FIXIT" could not detect any optical device...
Help, anybody.
Thanks in advance and best regards.
DH