Network Printers Disappear after Restart

Hello All,

We have XP and Vista computers joined to our domain. We found out that every
time the user restart the computer, all the network printers that had been
added in the previous login are gone. The user has to readd them again.

A different user tried to logon and reproduce the same thing, and got the
same result, so it's not a user profile related issue.

If the user just logoff and logon again, the printers stay there. Only
disappear after a restart.

No startup or logon scripts for the printers are running in that domain.

No error when try to add those printers. They are all added without problem,
and user can print to those printers, until the next reboot. Print Spooler
services is always running, no printer spooler error.

I hope you can help me

Thank you and regards