Do they have permission to install software and devices in general. The install driver allowance, only allows them to install drivers, but doesn't allow them to install devices.
By default, normal users don't have the permissions to install devices. To install devices the user needs to be an admin or power user, but I will have a look see if I can circumvent this with some group policy hacks.
I'll let you know if I come up with anything.
You could use restricted groups to give users that need it temp elevated privs. Or create a AD group for installing printers, elevate that group to power user, and when a user needs to install a printer, you can add them to that group for a short time, for them to install, then remove them.
Hope this Helps.
Neil J Cotton
njc Information Systems
Systems Consultant