All users on the network have antivirus software; however, several users report that they have what an administrator described as a "browser redirection virus." How can the users have this virus if they have updated antivirus software installed?

Users on a network can be affected by a ' browser redirection virus' if they open some browser being targeted by which they have subconsciously downloaded some free software called 'freeware' containing the virus on.

Explanation:

'Browser redirection virus" is actually a browser hijacker which may take over some functions like search engines, etc on a  browser used to download some freeware from the internet. It is often referred to as a Potentially Unwanted Program. Various browsers such as Safari, Google Chrome,Internet Explorer, Mozilla Firefox, etc may be targeted by persons with malicious freeware on the internet and while a user may knowingly download the freeware he/she needs, he/she may  have unknowingly downloaded some malware alongside, such as this Browser Redirection Virus. It basically redirects your home page, whenever you open the  browser, to the programmed ones  of  the attacker such as some other search engine, advertising sites, affiliate sites for products marketing, etc.    

The updated antivirus on the user system does not positively detect this as it is not a virus actually but some potentially unwanted program attached to the freeware downloaded from the internet by the user. This Potentially Unwanted Program is uploaded and attached online by some unscrupulous persons basically for some financial gains as it redirects your own page to those of  their own affiliates.

Hope this helps.

answer; ///shut the compressor off.