As the problem is the same even installing Ubuntu Precise from scratch, I'll just quote Peter Lehoczký (peto-lehoczky):
"Same problem here. After upgrading server to 12.04 (from 11.10) I cant print using samba from Windows desktops or Ubuntu desktop. From desktop ubuntu it keeps asking me for password when I want to print, but it wont accept any."
As the problem is the same even installing Ubuntu Precise from scratch, I'll just quote Peter Lehoczký (peto-lehoczky):
"Same problem here. After upgrading server to 12.04 (from 11.10) I cant print using samba from Windows desktops or Ubuntu desktop. From desktop ubuntu it keeps asking me for password when I want to print, but it wont accept any."