ACCESS DENIED, UNABLE TO CONNECT

Hello,
I am having similar issues with networking my HpLaserJet 4200 printers. I have 22 computers and 2 printers that are locally attached and shared out. Some of the computers will pick up the printers and others will not resulting in the "access denied, unable to connect" message. When I am adding the printer it asks for the logon and password, once I have entered the information it will say "windows could not connect the printer, operation could not be completed". I have successfully pinged the computers and the passwords are correct. I have tried adjusting the permissions on the computer the printer is locally attached to, as stated in some of the previous messages. I have also enabled the guest account! Nothing is working, HELP!!

Misty