That's a nasty program the copies the look of many other legitimate programs and is just waiting to catch the unwary.

From a site I find very helpful, http://www.bleepingcomputer.com/:

How to remove Antivirus Plus (Uninstall Instructions)
Posted by Grinler on October 23, 2008

What this programs does:

Antivirus Plus is a rogue anti-spyware that uses false advertisements as a way to convince you to install their product. Once installed, Antivirus Plus will be configured to start automatically by launching the file C:\Windows\system\rundll32.exe. Once launched the program will scan your computer and state that your computer is infected with a variety of malware, but does not allow you to remove anything unless you first purchase the program. While Antivirus Plus is running you will also see frequent nag screens stating that you should purchase the program as well as fake security alerts stating your computer is infected. Furthermore, this program will launch a pop-up Window that pretends to be the Windows Security Center. This Window is just another advertisement trying to scare you into purchasing the software and should be ignored as it is not the real Windows Security Center.

The rest of that information is here. Scroll down the page and it gives you information for removing it. You may need to pick up another free program to get rid of it.

SRS