Neither the printer or the driver can change itself, so whatever caused it was on the PC.Completely remove the driver/printer, then reinstall the driver and see what happens.
Its the banner page. Unknown happens because you are using a RAW port, Port 9100 is RAW
If you switch the LPR, it will show your username in Windows on the sheet
Or you can disable the sheet via the print driver
Whenever I print i get an extra sheet of paper saying "Unknown @Port 9100".
What does this mean? I can't seem to find any relevant info online.