Windows 7 pro. 64 bit & exchange server.

Qs
I am unable to connect to the exchange server from windows 7 pro. computer.
There are two windows 2003 servers on the network, they both communicate with each other.
The exchange server is installed on Server A, the windows 7 pc is connected to Server B.
What I did in the past on windows XP workstations, I modified the host file, and I was able to connect to exchange server with no problem. However with windows 7 I am having a difficult time. I can ping the IP address of the exchange server on the windows 7 pc, and vice versa, but I am unable to ping the host name (Server A).

Firewall is disabled, no antivirus software is installed.

Any suggestion?