I got a peculiar problem with an enduser today. He says for the past month or so, if he has a window open (not maximised) and he clicks the window below it (also not maximised), it won't switch to it. For example, if he is in Lotus Notes, and wants to go back to Firefox, and he clicks the Firefox title bar, the tasks don't change focus/switch to it. This doesn't happen for applications. Usually it is with Firefox but if he's in Matlab and goes to PADS for example, they switch fine. If you close the apps, and reopen them, it'll work, but about 30 minutes later the weirdness then resumes.
Any insight would be greatly appreciated.