Network Printer issue

Hello every one!
I have a print server (HP JetDirect500x), There are 2 printers connected it to it. Now there are 3 people in the office using these resources but when a specific user turns off her computer the rest of the users won’t be able to print to it, but if one of the other users turn off their computer it won’t affect it.
When they can’t print I get the following error message ( the printer spooler is not running) and as soon as this specific user turns on her computer I will be able to print to any of those printers.
Please Help me!
I’ve never seen this before.
thank you
Cesar