I really need help i have this problem in my computer every time i go in the Internet this pops up?

Yahoo Search Error!

Your computer is infected! Some of your search results were changed by spyware. You have to clean your pc and Yahoo Team recommend to use our ANTISPYWARE!

and it also asks me that they recommend me to download ''IE Defender''

I used Norton but it says that is all secure my computer

I really need help i have this problem in my computer every time i go in the Internet this pops up?virus

Oh boy...You have Smitfraud and/or Vendu on your computer. NO PROGRAM gets trid of these. You'll have to download all these weird little programs and fixes then reboot in safe mode then do all this dos crap...it's INSANE. If you aren't very computer savvy, you might as well just reformat your hard drive and reinstall windows.

I really need help i have this problem in my computer every time i go in the Internet this pops up?anti virus

http://www.stopannoyingpopup.com

Prevents from any unwanted popup ads immediately and automatically.

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Run quietly in your system tray using very little resources.

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Go to http://www.popup-remover.com

I use that program.It works very well.

Block pop-up ads and remove spyware .
Norton is crap. It rarely actually catches anything and it makes your computer unstable while doing it. It slows down everything and is essentially a front end for services that already exist in Windows or much smaller less memory intensive versions for free elsewhere.