I found this .inf file on Mustek's European site. It solved a problem Windows was having with the proper identification of my Mustek 1200LS scanner AFTER I changed over from the Domex 318 ISA interface card to the (Mustek-supplied) Domex 3191 PCI card.
The .inf file set up one device category ( "SCSI-Scanner") and two sub-categories ("Mustek SCSI Scanner" & "SCANNER"). I addition to solving the system nags for an unknown device ,it also solved a freeze on boot-up problem I was having as well.
I help this helps.. Thanks.