Comment 18 for bug 690461

While on a desktop (pre alpha1 install) this or related virtually never happens, on a laptop with fresh install yesterday it happens quite regularly
It's not just hidden context menus either, all or some combo of these -
context menus hidden
no dropdown in menus
r. click on launcher icon - launcher goes black
unresponsive launcher icons

The temp 'fix' is however quite simple - opening any available dir. restores any and all functions