Help with spyware removal

My computer recently goes very slow. When I open IE, Some unexpected websites, for example qihoo.com, always pop up with the default site. Some spyware must be in my computer, but I could not find and remove it even using Spybot and microsoft antispyware. Is there anyone knowing how to solve this problem? Your help will be greatly appreciated.

simply download antispyware from

http://www.microsoft.com/downloa ... &displaylang=en

and run it up.

you woundn't be disappointed.

Thank you. I am going to try.