Network printer - not seen from other

I have re-networked my Epson RX680 that is attached to my XP machine, in win7 four times now (That makes 5 times in all.). It works for an unspecified time then disappears for no reason. Win7 will not "See" the printer anymore. I have to start from scratch, and reinstall the drivers every time. I should be able to install a printer without resorting to '\\computername\printername'. My other XP machine networked to the printer, works fine, and has not dropped the printer.

The printer on the XP machine has been shared, and works fine in Win7 every time I reinstall it. Is there a problem with Win7, or am I doing something wrong. I've networked a great many printers, and never had a problem.

Add info: The XP machine with the printer installed, IS sometimes shut down with the Win7 machine still running. this would cause the printer to vanish off the Network, but in my opinion that should not matter. When I go to re install the printer, it is always clearly visable on the network when I click Add Printer. I am asked to re instatall the drivers every time I add the printer back. I lack the technical knowledge to check and see if the drivers are still installed, and the OS cannot find them. I should be able to run the networked printer without drivers on the Win7 machine, but perhaps this OS is different and needs them.(?)

This is extremly frustrating. Can someone help?