Eeep.

What happened? How did you get one?

i don't know how. but it make me can't do the regedit >.< also it doesn't allow me to update my new antivirus

Oh, those! I've had one of those before.

What I did is I found out exactly what kind of virus I'd gotten through Google, and I used Combofix on it. Worked like a charm. ^_^

I'd personally recommend getting a firewall. Sure Antivirus programs can fix the problem once it's taken root (sometimes) but a firewall will block it from happening at all. I've got Zonealarm Security Suite and it's served me well. They have a free firewall you can download from their website.