I was getting the same launcher crash issue. My system was vista 64 ultimate, had installed crysis wars, played a game, patches, played a game, installed MWLL, crash loop.
So i used the workaround and manually downloaded/extracted the client and all patches in order, and lo and behold, it worked.
So without any real software expertise i can say it's something to do with the launcher. Thanks for the workaround though!