Got them together. I didn't have to install them separately. The file size on the main folder is
5.61GB (Game of the Year Edition)
Everything works flawlessly, it's just this one campaign. The process that I normally follow is to click on any one of the campaigns, select New Game, and confirm to restart the game. The game launches successfully, and so I can start a new game or load a saved game for all of the campaigns except for just one -
Champion of the Arena.
UPDATE: It seems that the game decided to unfreeze itself after a while. The hourglass finally disappeared and turned into a mouse pointer. It's all working now! I don't know why this campaign takes longer than the other campaigns when it comes to starting up a new game or loading it. 
FIXED:
http://forum.1cpublishing.eu/showpos...7&postcount=24