Getting redirected from google and ask.com

I don't know what this falls into but after I log on and go to google or ask, com and post my question or what I am looking for the list of sites comes up. When I click on any of the sites listed my computer starts to go to the site but then gets redirected and I get a quest page saying that it can't find the site or it does not exist or the window show "jump" and it goes anywhere and a lot of the times it will not let me go back and type it in and I have to start over. However when I type the address in the bar it finds the site just fine. My system is a dell with windows xp or prof. (the sticker says xp, the system says prof). I didn't have this problem when I bought it, and I really don't know when this started. I do have the pctools spyware doctor but the scans come up empty. Could somebody tell how to fix this or what is wrong with it I am getting really annoyed by it. I thank everybody and anybody that can help me out. Thank you very much.