Live Mail crashes computer after Windows 10 “critical update”

I allowed installation of a  Windows 10 update today.  When completed, I tried to open Live Mail and system crashed.  I've tried to go back to the restore point that the update created but it fails saying that it might be anti-virus blocking blocking the restore point despite my having shut down anti-virus.  I've tried this about 5 times with same result.  Error message on failure when trying to open Live Mail says "irql - less or equal" as being the stop code.    If i need to reinstall Live Mail, I need to save mail in the system so don't want to wipe everything out. Any help appreciated.