I can show you a better solution than bootcamp. You can play it directly (and any other DOSBox game) on OS X using Boxer: http://boxer.washboardabs.net/ Boxer is free and really easy to use - the most work you have to do is install the game on your windows partition (to get the game out of GOG's windows .exe) - which you've already done - and then bring it over to your Mac side and install using Boxer which is literally a drag and drop for GOG games. This is how I play my DOSBox games, including MoO2.

If you want to play the Windows version of MoO2 rather than the DOS version (not much a difference between them - the DOS version is probably the one you want to play), use Wineskin: http://wineskin.urgesoftware.com/tiki-index.php - it's free and relatively easy to use for a game like MoO2. Wineskin can also be used to install your DOSBox games on your Mac side before transferring them to Boxer. Since you already have MoO2 installed on your windows side, this step is probably not necessary.

Save bootcamp for when you have to use it :) Another forum user, Rampancy, has a detailed explanation for how to get your GOG games working on your Mac partition, covering both DOSBox games, like MoO2, which are the easiest and Windows games which are the hardest. http://www.gog.com/en/forum/general/gog_games_on_mac_os_x_a_how_to/page1

Someone else however was having trouble with Windows 7 and the game similar to what you describe (they were on a PC, not a Mac). I think MoO2 was working on Win7 on Bootcamp for me, but again, you should just be able to use Boxer (or wineskin, but probably Boxer) and run it on your Mac-side, no booting into Windows required.

If you really really want to play it on your Windows partition, have you tried the basic diagnostics? Running the game as administrator? etc? Are you using the DOSBox or Windows version of the game?