Printer vanishes on XP when shared.

We have a new printer and three PC's use it. When adding the printer directly

there is no problems at all, I shared it onto the network with no problems

but now it vanishes every morning. I have added it correctly, done all the

usual tests to check it is working and no problems until the PC is restarted

and logged back in, I have to re-add it every single morning.

I have no idea why it is doing this, there are no errors involved and yet it

vanishes even if it is a default printer.

Any ideas? HELP!