It seems to be random but I have an error causing C&C95 closing at anytime during gameplay on Windows 7 64bit.
I have the 1.06r patch and HIFI's ddraw.dll running if that helps.
Also it's the First Decade version of C&C95.
Here's the screen : http://www.fotoshack.us/fotos/6653C&C%20issue.jpg
Other system specs are :
Resolutions I've tried with ddraw are 640x480, 800x600, 1024x768 and 1920x1080 and it happens on all of them