Re: command and conquer 3 tiberian wars resolution
Everything going dark except for the validation message is pretty much expected behaviour, and isn't at all what I would raise an alarm over. Nor would it destroy your installation in any way.
By the way, C&C 3 has a limited set of resolutions it natively supports. To use custom resolutions, go to this location:
C:\Users\[USER NAME]\AppData\Roaming\Command & Conquer 3 Tiberium Wars\Profiles\[C&C 3 PROFILE NAME]
There, open Options.ini with Notepad and find the Resolution value. Set it to whatever you wish, but don't put the "x" between the numbers. In your case, it should look like this:
Resolution = 2560 1440
...and NOT 2560x1440.
Save the file and run the game again. The same goes for the Kane's Wrath expansion, as well as Generals, Zero Hour, Red Alert 3, Uprising and Tiberian Twilight.