Changing Win7 taskbar position messes up screen?

[Gurachn]

Tried unplugging the external monitor, rebooted, and fired up the game on Desktop res/windowed (1366x768) with the task bar still at the top.
The screen came out fine, but their was a space at the bottom and the top bar of the game was hidden under the task bar.
It seems that it wants the task bar to be at the bottom.
Plugging in the monitor again, even with the bar at the bottom results in the strange diagonal skewing.