I've just installed 12.04, configured it according to my preferences and started working, when I noticed that some buttons (e.g in context menus) are inactive (grey) but I can still click them. They randomly become active and inactive. Sometimes its a paste button (of course i clicked copy earlier ), sometimes rename, 2 out of three times i run Transmission Bit torrent, its buttons are inactive (but still working). I'm not a total noob in ubuntu so I don't think that's a matter of my incompetence or lack of knowledge. I don't think i did anything to mess it up. I tried to look it up on the internet but all I could find was a few people reporting it as a bug (with no response or solution).
Did anyone encounter the same problem and, hopefully, solved it? It is really annoying.

Thanks in advance!

Emil G.