After add the Cisco ASA5550, my server can't access the internet

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http://serverfault.com – Here is my network infrastructure. there is a problem in my network. server M,A,B,C,D have public ip address. people who are outside of my network can ping server M at anywhere, but they can't access server M. server M can ping any ip address on the internet, but it can't access any ip which is outside of my network. server M can access Server A,B,C,D, and A,B,C,D also can access M. A,B,C,D works well. people can access them at anywhere. when I exchange A and M in my network. I just change the ip information on them. the new A works fine. so I make sure the configure of server M is OK. (HowTos)