I've been tried all your suggestion, but I still can't online regristration. And then I've tried to reinstall Windows because my analize that my computer have been attacked by viruses, it's been seen that I can't reinstall or uninstall avast even I can't deleted/removed avast from program files. After reinstall a fresh windows XP finally I can install avast and update it.
Finally, thanks to all of your suggestion,
Note : I'am sorry if my language is very very bad, because I'm Indonesian.
My trully regards,
Bagus.