A first step would be to search all widgets gadgets for "MouseRelease" and then maybe add some debug prints Spring.Echo(...) at the start of those to help you find which was the last one that executed before the hang.
I can search all normal widgets in my widget dir for Mouserelease but 'adding debug prints' might be a big over my head. Dan i copy Spring.Echo(...) at the start of the line in which mouserelease is? Or at the start of that section? Should there be something in between the brackets? (...)
In the unlikely event that this still yields nothing, another option would be to temporarily remove/disable the "MouseRelease" code first in all widgets/gadgets just to confirm that it helps and then in one at a time until you have pinpointed the bug.
The crash shows up very irregularly (as in, i could play 10 games in a row without problems and the next few games it happens multiple times).