I would suspect USB hardware and the drivers for it (which probably are not the same between your wife's PC and yours).
I had similar issues, but back in win7 when my DAW (offline) would take ages to shut down or just get stuck shutting down; I could never 100% trace it (thus not eliminate it) but very often it had happened after I had issues with the audio driver in Sonar, when it either crashed Sonar or made me manually close Sonar and go for a reboot ...
For me these "shutting down takes forever" issues have disappeared since win10 (which reinstalled all device drivers), but I have also swapped some USB hardware (MIDI and audio at about the same time)
I would try running the PC with only mouse and keyboard on USB, everything else (printers, cameras, external drivers, whatever) unplugged.