Block internet access for single desktop

Install the browsers back, you might need it for internal use.

1. Simple way is to configure the connections to go through a proxy server with a 'bogus' proxy server address. In that case, it will always try to go through it and will never reach since there is no proxy server at that address.

For IE;

Tools->InternetOptions->Connections->Lan Settings-> set up a bogus address (something like 1.1.1.1 and give any port you want).

This will work if the user is not computer savvy.

2. Another way would be to 'remove' the default gateway from that machine so that it never leaves the local LAN (assuming you are on a single network).

This will work again if the user is not computer savvy.

Will go into more detail if these 2 are not options.

Cheers,
Rajesh

Remove the default gateway on the PC or point it to a machine other than the ISA server. Also remove the ISA client if it is installed.

I was able to figure this out. In my ISA Firewall management console, I had a policy for unrestricted internet access, under this rule I added the user and computer in question to the exception, thus blocking them from using the internet.