An environmentalist attack on Morgan Stanley Dean Writer & Co. shows how difficult it can be to keep today's amoeba-like global companies out of trouble. At issue is China's Three Gorges Dam, now being built in mountainous Sichuan province. The dam will force more than a million people from their homes along the Yangtze River's banks and turn the mustard colored waters of the river's upper reaches into a tremendous lake. Environmental activists inside and outside China oppose its construction.