In my case the frozen��Pharo window appears to have an image that was put��back into the wrong resolution (I see colored pixels like a P10 window, but they're misaligned). As far as��I can tell, the image doesn't respond to keyboard shortcuts, etc. I have to kill the image in Explorer.
My setup involves multiple monitors, with different pixel sizes (windows allows to scale them according to the monitor). Perhaps that is part of the problem? It affects Pharo Launcher itself, too, which is running Pharo 10 according to a playground window (SystemVersion current version)
Next time I will make an issue on pharo-project/pharo with a screenshot.