Sketchup 2015 Install crashes Windows Explorer

No extensions were installed, and 2014 was uninstalled at the time.  I did not try disabling GPU acceleration, but Windows Explorer was crashing repeatedly after fresh reboots and with no copy of SU running (when deleting 2014 .skp and .skb files).  When I uninstalled 15, I was able to delete SU files without crashing Explorer.