Cisco Firewall :: 5540 Http Failed To Send Data To Server

I have one server-A(windows 2008) installed one application called"host front" which gives athentication to connect Linux(mainframe console) server (SERVER B).These 2 servers are bihind the firewall.If one  internal user who has the athentication to logine server-B ,tried to login server A,will get the" username and password"screen and once they enter the username and password ,will get the server-B screen.But if somebody try to connet via MPLS(we need to test MPLS site customers) from outside via ASA 5540 ,to server-A will get the "username password" screen and once enter the credentials, after 1 minitue will get error"http server faild to send datas to the server" and will not move to server -B screen.