I spent an hour wondering why the **** I couldn't get No.1 son's PC to print to the Laserjet on another home PC, as I had just built him a new one following PSU failure on his Compaq PC (and Compaq PCs have bespoke PSUs that are not realistically replaceable).
It finally dawned on me that I had set logon time restrictions for him on the remote PC (to which the printer is attached), so his credentials were rejected outside of his allowed logon time.
Doh!
SD