Printing via RDP - Terminal Serviecs

I'm having a problem on a small network with printing via terminal services. Here is the scenario:

Desk A connects to one of their client's systems via terminal services to collect billing data. They are able to connect to the client's terminal server using the built in RDP client in Windows XP. When they connect, they are able to access the client's database and print to a local printer at Desk A. No problems whatsoever.

Desk B can also connect to this same client's system, but cannot print. When they establish the RDP connection, their local printer is not detected/install in the terminal session.

Both desks are using Windows XP, are members of the same domain, have the same permissions, same network configuration (including firewall) and both are using USB ports for their printers. Desk A is using an HP All-in-one printer and Desk B is using a Dell 1720.

I'm told by the owner of the company that their IT people installed the driver for the Dell 1720 on the terminal server, but not the driver for the HP All-in-one. Why the HP at Desk A works, but the Dell at Desk B does not is very confusing.

The only indication I have of an error I've gotten is in the attached screenshot. This occurred when Desk B logged into the client's terminal server. The research I've done says that this is a drive mapping error, but still unsure if it could be related.

Thanks in advance for the help.