Vista - [Emergency] Network suddenly crippled

My main machine is running on vista, since last night, all the network connections suddenly appears "limited connection". I tried repair, disable, renew ip and everything, none of them worked.
It is on auto acquire IP and gateway.

What might have caused this sudden cripple? I plugged the internet cable into my laptop and my laptop gets internet perfectly, so it must be something wrong with my main machine.

The only thing I can recall that I did before it happend was that I reboot into a linux live CD called BackTrack3, my friend gave me a copy of that and I tried to play around with it. But I was too rookie to understand most of the tools so I went back to Vista, and then the internet suddenly broke.....

Any ideas what might have caused it? Thanks

Have you tried using a static ip address

More than likely the pc went to sleep and lost connectivity when you woke it up... you say you restart it again and lost connectivity right after that?

Things I would try.

If you are only behind a cable modem, reset it and restart your PC.

If behind a router, reset the cable modem, restart the router and restart the pc again

It should come back again.

Who is your ISP anyways? If comcast, be careful, I spent the morning and afternoon dealing with the same problem and at the end... Comcast was fixing something on the hub nearby and were down all day. I got it back all on its own later on that night