Avast 5.0.594 Printer Sharing

I have 2 XPs on workgroup with a printer installed on one box. With 5.0.594, I have to change the firewall from “Medium” to “Low” in order for the second machine to talk to the printer. Is there a way to set up a rule to allow this communication with the firewall in “Medium” so both machines can use the printer. Would the sandbox be useful to isolate print routines?