I can confirm that I had this same exact problem when creating plugins.. Was really annoying.. Though the exact same plugin that were hanging on me didn't always hang on others... And also sometimes it seems to be "Random" times it does it.. That means if it starts doing it, it can be stopped by a restart, other times a restart doesn't help.. At one point I really had problems with it hanging.. All the time... So.. Because of this I really hate using the DisplayToast() Function...
To clarify, it's in VB, and MSN didn't Freeze completly.. Just a 10 secs hang.. Or there abouts..
I didn't really know this was a problem that other users also faced, so i've always thought that it was a problem with my computer.. Now I see it might not be... So.. I hope this can fixed..
.... Would really be nice...