Twee
I would guess that the printer is not recognising the document formats, but this should produce an error. There may be a conflict between different software. I have had similar problems where I have had different printers and have just added the new printers software, without removing the old. I think the PC just gets confused.
If your Dad still has the original installation disc for the printer, I would remove all printer software using uninstall options in program list, restart the PC and then run the installation disc again.
If this does not solve the problem, PASS.
Huckster