Updated to latest build. New project..
Selecting anything in App Explorer window, as well as focus on the tab of App Explorer window causes Problem Occurred pop-up error message. Same happens when computer's toolbar items like Power or Volume are clicked while App Explorer is in focus:
Different message occurs while App Explorer is focused and Launch Button is rolled over:
Behavior varies according to window/window group placement. For instance, when the window is not grouped along the right side from top to bottom the issue is not persistent.