Math-o-mir beta8 is here:

Very strange bug in the last beta7 – FileOpen and FileSave dialogs misbehaved on some systems causing application to semi-hang when one of these dialogs opened.

You can bet I am sorry for not seeing this problem 7 hours earlier!

This time the bug was not in my code, but in the MFC code. Still, the bug is very embarrassing… I wonder how many users downloaded the problematic beta 7 in last 7 hours. I can only hope that not all of them experienced problems (on 2 of 3 machines in my possession the problem is not visible).