Trouble starting Defcon (resolution/screen issue)

Hi guys,

I'd appreciate any help or advice you could give me - please bear with my description of the problem, but I'm stumped. I'm experiencing the same issue on both me Windows 7 (64-bit) system, and my Mac OSX 10.8.1 system. I recently bought a new computer and tried to install my retail version of Defcon onto it. This was a boxed retail version of the game, compatible with Windows that I installed onto my Windows computer. Although the install appeared to work correctly, when I launched the game, it opened up "offset" - ie. the screen was cut off at the top and right hand side - I could only see the bottom left of the launch/home screen. In addition my mouse pointer wouldn't track all over the available screen - my mouse pointer would hit an invisible wall halfway down the screen and Windows thought I was at the start menu / system tray. I thought this was odd, tried changing various resolutions and selecting 'open in windowed mode' but nothing helped. So I decided to download (and buy!) a new copy of the game, from Steam on my Mac system. Despite being a completely different system, and bought through steam (which correctly plays my other games) I had the exact same issue. Does anyone have any ideas?

Please help

I didn't find the right solution from the internet.

References:
https://forums.introversion.co.uk/viewtopic.php?t=8511
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Thanks