As of about two weeks ago, my WinNT machine has a new way to annoy me. While I'm moving the mouse (nowhere near the task bar, mind you), it'll suddenly tile all my windows, pop open an "Open Microsoft Office" dialog, and open some configuration dialog. (Fortunately I was recently handed the clue I needed to undo most of that in one operation, though "Undo Tile Windows" will often leave one window still at the wrong size for some reason.)
Today was a new one -- it shrank my browser window down to just the title bar and moved it to the bottom of the screen. I have no clue why it's doing this. It's frustrating.