Some of my games won't work.

This error means that your chosen resolution (probably the default resolution if you didn't change it) is not supported. You will need to change the resolution to be able to play these games. (Try 1280 x 720 )

Get the community patches from here (those contain a config program which allows you to change the resolution):

cnc1: http://nyerguds.arsaneus-design.com/cnc95upd/cc95p106/

Red Alert 1: http://funkyfr3sh.cncnet.org/

Tiberian Sun: http://cnc-comm.com/community/index.php?topic=3438.0

For Red Alert 2 there is no patch you can download, that means you need to go to the game folder and modify ra2.ini and ra2md.ini manually, the settings are looking like this:

[Video]
ScreenWidth=1280
ScreenHeight=720

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If it still doesn't work after the patches/changes then it could be related to your windows DPI settings, make sure you have those set to 96DPI / 100% - Tutorial:

http://www.sevenforums.com/tutorials/443-dpi-display-size-settings-change.html

I've managed to get just command and conquer working, i've changed the settings in RA2 and still same error, along with tiberian sun. I've followed every step and it is at 96 dpi and whatnot.

if command and conquer works then red alert 1 will be working too, what resolution did you choose in command and conquer? Did you try the same one in TS/Ra2?

Keep trying some more resolutions, it just depends on what your PC supports. The tiberian sun config which was added by the patch shows you a list with all supported resolutions, go through all of them until it starts up

CnC1 and RA1 will be working fine in window mode too, that's another way to bypass this error. TS and RA2 will not be working in window mode on windows 8 without flaws