You click the radio  button and that sends a message to the server, the
Process.Start occours on the server NOT on the client machine.

Ok, you figure, if your on localhost then server/client are one machine .... so
it should start  the process.

Well, it might, if you gave the correct  server folder permissions admin
authority execute etc.

But as soon as the code  is put onto a server somewhere else - they will
definately NOT gve you permissions to start running processes on their machines.

It will however work in a Winforms app locally - which you could embedd into a
web page, send to the client and, using interop(again with permissions) access
the client computer and open anything from IE to Word.