This sounds like ye olde crasher bug in GTK when the filesystem contents changes and a file chooser dialog is showing it. AFAIK, it should have been fixed a while ago in GTK, though. I'm not sure which version should have fixed it and I can't seem to find the bug reports just now, but if the GTK version we bundle on Windows suffers from the issue we might wanna try and get a newer version (yeah I know how annoying it is).