I am using Windows 8 and not Vista or Windows 7
I have not found a button in the Windows Explorer labelled "Compatibility Files".
I have, however, more out of desperation, with the Windows search function searched for "SC2.ini".
As result a config file was found.
After I mentioned "The Assault on Democracy Demo" runs on my PC, I have compared the config files of both programs and found that in the config file for "WWI" the values:
#window_width
#window_height
both were set with "0".
After I have replaced these two values in the config file of "WWI" to 1280 and 1024, as they are set in the config file of "The Assault on Democracy", WWI runs again.