I had 8GadgetPack 5 installed, that's the only thing I could think of; uninstalled that now, rebooted, reinstalled Start8 (1.12) - rebooted - still the same - see vid
This happens every time when opening the context menu and hovering over it, or clicking sth. left or right click... The next operation that involves explorer will then let explorer crash / restart. Everything else keeps working.
Unless the GadgetPack leaves sth behind after uninstall i have no idea what else could be causing that.
Wait: I installed some other Start-Replacement (Startisback 2) for comparison that opened instantly over Start8 after installation. That made my pinned items in Start8 disappear, even after uninstalling Startisback. Maybe that caused some lasting error.
Next will try uninstalling Start8 completely and reinstalling it instead of just installing over the existing installation.
edit: that did not help, either, still the same...