This just started happening with the latest build, and I can't seem to pinpoint the definitive steps it takes to reproduce, but *generally* is happens when:
1) download new headers
2) open one newsgroup folder, then close it
3) try to open another folder
If I keep the first folder open, NB doesn't crash when I open the second. It also seems to be OK when I have more than one folder open, close just one, then open a new one. Make sense?
Win 7/64, i3 2130