PO20 printing paper copy of PO

unknown

We are experiencing intermittent problems with printing a paper copy of our PO's. Some days they will print with no problems and other days it stops working. The only change we have made since this issue started is we upgraded our Lawson server to a new Unix OS and upgraded our Lawson environment from 9.0.1.11 to 9.0.1.13. Has anyone else experienced this issue?