Rushes, I have Microsoft Security Essentials and I went into my settings and excluded the game. Well, that didn't work!
I don't think Microsoft Security Essentials is the problem. It generally doesn't interfere with games, so turning it off wouldn't make any difference. Have you tried setting the compatibility mode of the game Launcher as Inland and Draclvr suggested?
Do you know how to locate the game Launcher? It should be in the game folder. If you don't know where the game is installed, right-click the game shortcut, choose Properties, choose Shortcut tab and you should be able to tell from that where to look for the launcher. Right-click the launcher, choose Properties, choose the Compatibility tab, and set compatibility to XP SP3.