I can't consistently reproduce the strange behavior.
Menu items ghosting.... etc
just restart the system.
Well, I won't worry too much.
Seems to be a hot day (poor cooling on the system), stressed CPU, etc. etc.
I have this in the past too, now very few occurences... but, don't worry: you can't reproduce it because it's not a deterministic problem, you can't 'solve' it.
Boot, boot... the drug of the drugs