Print settings are greyed out

Hi

When I open a PDF I can print it to the printer/plotter, but when I try to print another PDF, all of the print settings are greyed out and I can't select anything to print. I need to close the program to print again, but I can still only print one document before having to close PDF Architect again.

This only started in the last week or so. Can anyone help me with this?

Thanks.