Of course the other possibility is that the .prt file for the default printer, whatever it is, is missing. Look and the entry for the printer designated as PFPRINTER in the filePro configuration file and make sure that the .prt filename is correct.
The printer is defined by three comma separated values. printer name, .prt filename, dest. command.
One of my printers shows...
hp-4,hp-4,lp -d ljet4 -s
In this case filepro expects to find "hp-4.prt" in ../fp/lib