I see the printer on my Win 7 box but cannot print from new Macbook Pro

I am getting a support code 306 communication error while attempting to print from my new powerbook (mountain lion) to my networked Canon MX850 that is connected to my windows 7 box/print server. I cannot print a test page. I can see the printer from the workgroup. (but note it won't let me connect as registered user, only as guest.) I have updated all drivers and software. I have removed and reinstalled. I CAN print locally to the printer if I bypass the network. I have removed and added sharing on windows, added every possible permission I could find. Note the user names are NOT the same between the win 7 box and the Macbook pro, but the passwords are. Suggestions?