Yahoo and Google Searches Are Being Redirected?

Every time I search on Yahoo, Google and Bing, the results I click on are redirected to another website which is garbage--actually now, I can't even search on Yahoo because it gives me the 999 Error and Google keeps giving me the captche page to deter me away. I have searched for answers but nothing has helped. I have: Spybot Search & Destroy, Malware Bytes, Super AntiSpyware and Spyware Terminator and not one of them has found anything! It's getting old, so how do you rid of this dam adware thing after all?