Loading DXF Files Into ProCad

DXF files are supposed to load into ProCad. My son created a simple line drawing with some dimensions in AutoCad on a PC and sent it to me as a DXF file. I opened a window in ProCad and dragged the DXF into that window. A window appeared headed “Input Scale Factor” with a value of 0.00203222 showing. I hit okay and the timer appears but the file never opens. The timer does not move if the mouse is moved. Alt-Break does nothing. Ctrl-Shift F12 does nothing. I have to cut the power and reboot to regain control of the computer. ProCad is v 1.09 and I am using RISC OS 5.27.

Can anyone suggest if there is anything I can do to get ProCad to load the DXF?

I import DXF files from AutoCAD without problems but I use 1 as scale value. Before I Do anything more I save it as ProCAD.