[5.50.09b] Window mode and 1280x1024 gives error

[EagleMountainDK]

Hi,

I've just installed CCLD again, and ran it just fine. I then sat the video options to 1280x1024 and window mode. I then restarted the game and every time I start the game, I get the following message:
"There is an error with your serial number as entered. Please contact support@matrixgames.com for assistance. Error Code: 18"

Can I in some way reset the game options, besides un-install and re-install?

My DxDiag: DxDiag.txt

[EagleMountainDK]

Oh well, I uninstalled the game. And reinstalled it again. It nows run in a window without any problems. Not sure what went wrong.

[EagleMountainDK]

And now its back again. This time with error codes like -11174845. I have tried to run as administrator and it seems it helps...