Try malwarebytes to clean up your system:
http://www.majorgeeks.com/Malwarebytes_Anti-Malware_d5756.html
Don't let the battalions of external parasites into your system in the first place: stop these guys @ your 'doorstep' & keep 'em out:
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INTERNET EXPLORER: Tools> Internet Options> Privacy> Advanced:
here check 'Override automatic....'; 'Allow session cookies'; 'Allow 1st party cookies' & 'Block 3rd Party Cookies'.
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FIREFOX: Tools> Options> Privacy: Check 'Accept Cookies from sites'
& Un-Check 'Accept 3rd Party cookies'
Firefox add-on's
Flashblock: https://addons.mozilla.org/en-US/firefox/addon/433
Add block plus: https://addons.mozilla.org/en-US/firefox/addon/1865
Popup Master: https://addons.mozilla.org/en-US/firefox/addon/1788
"NoScript" for Firefox will stop a lot of these adware/spyware & hijackers:
https://addons.mozilla.org/en-US/firefox/addon/722
Use this feature to block unwanted advertising re-direct:
With NS running, down on the far right corner is a blue 'S' with a red line through it: right click that> tick 'forbid -------' &/or mark as 'untrusted'.
(Ticking all may reduce interactive behavior; enable just enough to get what's necessary)
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Server based spy/adware, that tracks your surfing & builds a profile of your surfing: requires "Opt Out"...
Yahoo here: http://info.yahoo.com/relevantads/
Google here: http://www.google.com/privacy_ads.html
NAI garbage here: http://networkadvertising.org/managing/opt_out.asp
DoubleClick poison here: http://www.doubleclick.com/privacy/dart_adserving.aspx
SpywareBlaster for system wide, realtime protection:
http://www.snapfiles.com/Freeware/security/fwantispy.html
Turn off 'spell check' may help, as this sends keystrokes back to the server also, which may be used to 'target' advertising.
Good luck. :)