Mask - Can't access control points

I've crerated masks before in Motion without any problems. However tonight I drew after creating a mask (with footage sent from FCP), I couldn't access any control points or even the mask iteslf. This happened after deleting the mask and trying again, and even after quiting and then relaunching Motion. Another problem is that when I click to add a control point, the point is more than a few pixels away from where I clicked.

While we're at it, I seem to get more than a few force quits in Motion - could this be our video card, an ATI 9200 (I think).

Suggestions? Many thanks,
-Les

FCP 5.02 with Kona2 on a Dual G5 2.5