Connection status unknown

Hi. My computer was working fine last night, but when I started it up today, I couldn't get online. When I hover the mouse over the network and sharing icon on the lower left side of the computer, it says, "Connection status unknown The dependency service or group failed to start". When I try to diagnose the problem, I can't because the Diagnostics Policy Service is not running. When I go to the Open Service Control Manager, access is denied.

Meanwhile, I keep getting warnings that my firewall is not enabled. When I try to enable it, I get a message that the Security Center can't turn it on.

I ran Avast and it found nothing wrong. I tried doing a system restore, but that didn't help. I tried going to "Connect to the Internet" via the Control Panel and Networking and was told that the wizard encountered an error and could not connect. I can't connect and I still can't enable a firewall. What should I do? Please help me.

Do you have the original media that Vista came on? It sounds like you need to do a system repair if you are totally sure you do not have a malware or a virus.