samba / cups access denied

Hello,
i have several hp 4100 printers with builtin networkcard and configured them in cups. From the Knoppix pc i can print to all this printers without any problems. From a other winxp-pc i can see and access all defined printers too, but if i try to open a printer it shows that the access is denied.
In smb.conf i have under [printers] entries for guest ok = yes and printable = yes.
Fileshareing works, only printing gives problems.
Don't know if it is a problem with samba or cups. At the moment a assume that it is cups.