Completely recommend taking support to the manufacturers of the equipment.
Install all software recommended by adaptec, and the printer manufacturer.
Ensure that the scsi miss had been correctly terminated for power and signal.
It's been a long time since I've worked with scsi, so maybe some else can help with specifics.
Wouldn't expect an aspi layer to be required for this purpose.
Vista64 drivers should work fine in windows7, or failing that windows xp 64bit covers should work ok.
You may need to disable driver signing to install these drivers.