LR Classic 7.2 Freezing Windows 7 Machine

I've used this machine to run LR since I was using LR 6 without any problems (other than speed moving from raw file to raw file in the Develop module).  I installed LR 7.2 a few days ago and have had my machine freeze twice in the last two days.  My Windows is up to date and I checked plug-ins and don't have any weird preferences, although I do run everything off an external drive that looks like an internal one to Windows.

Any thoughts anybody?  I'm ready to back rev or look into Capture One.