Windows 7 Client Network Issue

Hello, i connected to a network in work group environments where server has win 2k3 and ISA 2000

and my PC which is client has windows 7 64bit ultimate edition. i use this network for internet connection when i set my setting in LAN IPV4 to Obtain Automatically then my internet is working fine while my network admin give me the following settings.
My IP : 172.16.0.99 Subnet mask : 255.255.0.0 Default Gateway : 172.16.0.1

when i set the above setting my internet stops working. even i point my browser to 172.16.0.1 : 8080 and other application who provide setting. but can't get access to internet. but ISA client succesfully detects the server 172.16.0.1 and LAN is saying unidentified network. what should i do successfully connect to internet.??

I'd start with a visit to the network and sharing center control panel and use the tools there to verify your network setup.

Well when i set the LAN with given settings i get unidentified network but works fine while set the LAN to obtain automatically then it works. its strange can't figure why when i install ISA client and set it to 172.16.0.1 it detects the server successfully but browsers doesn't connects to internet. even i configure browser to use that server IP but no use.