Windows Vista continually prompts me for a username and password for our proxy server. We have no proxy server. We have 30 machines on the network but only 1 Vista machine. The XP and 2003 machines all work great but my Vista machine will not connect to anything and is frustrating me this annoying popup. The prompt for username and password appears approximately every 30 seconds. How can I get rid of this prompt and connect to the network and internet?