Heroes of Might and Magic 4: The Gathering Storms HELP!!!

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I have just installed an old game i loved which is Heroes of Might and Magic 4. And i also installed it's expansion pack - the Gathering Storms, but i have encountered a very irritating problem. See, after i installed it, instead of fast loading of the game, it loads but very slow. I can't play it. Whenever i double-clicked the game icon in my desktop to launch the game, it runs but stops when it says "Loading...". The "Loading..." page disappears and then i just stare at my desktop without launching the actual game. Why can't i play it? Can someone help me in my problem? Thanks in advance and Godspeed!