Ok sure, will try that. Basically what happened was that my windows' title bars went missing (Title, minimize, maximize, exit) and a right click meant that it flickered before opening.
15% of the time on startup my titlebars are missing, too. a great solution for that is to install a Compiz Fusion Icon package - an applet sitting in tray where you've got lots of options to configure Compiz. One of them - and that fixed the missing titlebars with a whirl! - "Reload Windows Manager".
Bingo! And everything is back to normal. Tell me if you got it right.