Freerouter stalls

When I tried to launch freerouter from pcbnew just now it locked up with a message at the bottom ‘unable to read file gui defaults file’, and a dialog box saying:

Loading design ControlBoard.dsn
BshPanel.sourceBeanshelllScript: config.bsh not available
try open /home/derek/PCB/ControlBoard/gui_defaults.par

I’m running on Kubuntu, and this whole process worked fine last week with a simpler pcb.

any suggestions?