this might sound odd but i had the same problem and it turned out to be my graphics drivers.
they were making msn close if any window opened on my pc without direct input. for example if someone spoke to me or a toast screen.
check your drivers are up to date and also click the send error report, then follow it to the microsoft website which will give you details of what is wrong if you look hard enough
see my error bye seacrhing for "now this is getting annoying" thread. or click
here
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