Moved this to Malware Discussion > Home User Assistance for better attention.
You might also want to go the Hijackthis route as suggested near the bottom of this document to get a verdict from an independent forum.
By the way no antivirus, no matter what brand, can protect against 100% of what's out there. Just be very careful and never click on anything you aren't sure about, not even the 'X' to clear it if it's a popup.
That's how these new fake anti-malware pests take root.
You mat want to check this out to.To see if you have been infected By DNSchanger. http://www.dcwg.org/detect/ after you go to site just click the link.It will show you right away.
Nothing to download.I would take Ex_brit`s advice If The mcafee tool does not work.It would not be a bad Idea anyhow.Once a system Is infected you never really know if you have killed everything off. All of those help sites are very good although you may have to wait a Bit.I recently used spywarehammer & they were very good. Good Luck.
For the part where you are saying the webpages forward to other random sites, you may want to check your Hosts file located here, sometimes virus alter this file and place static values changing where sites go.
Another clenaing app you could try is Combofix which is a registry cleaner, it works pretty well.
Only download this application from bleepingcomputer.com, just to be safe.
You may also try cleaning the computer using the following tools
ATF Cleaner which is available at : www.virushandler.com\tools
if you are an advanced user try the Autoruns tool ,you need to be bit careful to use this tool,
download this tool, and run it, select Internet Explorer tab try to find sucpicious entries
Whilst the last two posters are no doubt trying to help it's not advisable to use these tools without adequate supervision unless you know exactly what you are doing.
If you aren't sure how to proceeed next with a problem use Hijackthis and post it's log on a forum that specializes in such things or try the other tools & methods - as suggested in the link I already posted.
Also @virushandler, it's against the terms of service here to advertise and I think your profile (& post above) would constitute advertising a website, I amended your profile accordingly..
Sorry not my rules but McAfee's.
By the way, one of those links didn't work anyway.