Airport Express Printer set up in Windows 7 but "An unknown error occurred"

I just purchased an Airport Express so I can wirelessly print from my Lenovo X201. After setting up the Airport Express to see my existing wireless network (solid green light) I used Bonjour for Windows to wirelessly locate and set up my printer that is connected to the Airport Express. Everything went super smooth and the printer was set up as the default printer. Then I tried to print. Upon printing (anything on the internet via Firefox) I get "An unknown error occurred while printing" and the print job immediately aborts (zero jobs have reached the queue). The error happens so quick that I suspect Bonjour failed to correctly set some obscure Windows setting that is preventing the job from being sent to the printer queue. I turned off the Windows firewall, but the error still occurs. What else might interrupt the print job...when everything else appears to be set up OK?

Message was edited by: VeryCleverAlias