Antivirus software is not working

Maybe I’ve loaded viruses on my pc forgetfully and there is Norton Internet Security 2011, installed but still it can’t ensure the security. When I’ve tried to fix the problem it appears with an error message which is:
“ORDINAL could 383 be installed in the Dynamic Link Library…. Iertutil. Dll.”
I know a little about the computer and I’m trying to learn. That is why I can’t fix the problem. Can anyone please, help me to fix it up?
