Trying to install shared printer on Ubuntu 8.10

[mike]

I am trying to install Shared  network printer on Ubuntu 8.10 , Printer is Epson D88 attached to Windows XP computer. I complete the set up, verify printer access etc ALL o.k until I try to print. I receive error message " NT STATUS ACCESS DENIED opening remote spool test page " then I am asked for authentification - user +  password. I entered these at set up stage but are not now accepted. I have NO passwords etc for my Windows Machine Access. Any ideas please.