Question: Help needed for correct Window resolution.

[Hviid]

I've got a new computer, with a window resolution of 1366 x 768. OS is Windows 7, home.
I have the CD version of WinSPMBT.
Upon installing the game, I set the "Screen/Windows Size" as "Desktop.
When trying to play the game, the game window comes up as a wide and low window. The same goes, whenever i set the "Screen/Windows Size" any bigger than 800 x 600.
The game functions correct when I set the "Game Mode" as "Full screen".

I've checked FAQ, Game Installation and Tuning Your Machine chapters in the Game guide, version March 2012, with no luck.

Somebody please help me to get the game working in Window mode.