Printing problem

We have printing problem. Windows 98 SE. Epson LX300 and Apollo 300 connected through selector switch to parallel port. Bios settings ECP+EPP.If we do not switch computer off for the night, then none of the printers is printing. Error message ?Can?t print to the LPT1″. If computer rebooted then it is possible to print. This problem started recently

Please let me know what could be the problem.
Vladimir