Like others have said, never, ever use meshsmooth unless you know exactly what you are doing. If you want something smoother, you can either chamfer an edge, or cut a new one. Only add polys when you need to in a localized area. Also, it's a good idea to save "stages" of the map (steps in development) every one in a while (and before anything drastic). That way if you screw up something you can go back. Seems obvious, but it saves you alot of pain...
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