Windows not appearing on Task Bar

[tomd]

When I have a window open on my XP machine, it doesn't appear in the task bar, but when I minimise it appears as a small heading at the bottom left, like minising documents in Word before each one got a seperate window. Is this a feature turned off, or is it a software problem?

[QmunkE]

You may have a toolbar open that is occupying the whole space. Right-click, go to toolbars and then uncheck them all. Or, click "Unlock the taskbar" and then drag the vertical lines on the taskbar about until you can see windows. Can't think of any other reason for windows not to show up.

[tomd]

Already tried that, was nothing open except when WMP minimised (into it's little miniplayer) XP SP2 seems to have knacked my computer, the sound card & printer drivers have stopped working as well as this, all immediately after SP2 install.