I fixed it the last time, but it is now back again.
The symptoms are exactly the same and I have the same specs.
Old Topic can be found here:Screen Resolution Problem

I've tried everything recommended in that topic, everything that I found myself and it still wouldn't go away!

Also, I noticed that it happens because I started the computer with the monitor off.

I've rebooted, tried system restore, uninstalled and reinstalled both graphics chipset and monitor, tried the GMod thing too.

Any help would be great as I hate wrongly set screen resolutions...