some antimalwares
First eliminate the temporary fils with this software (excellent): CleanUp40.exe - you also can find it for free - many malwares put themselves in Temporary Files; on the other find, you'll spare time for the scanners to do the scans faster (avoid these sometimes huge folder full of ****).
Then try this excellent software: Blacklight Kitroot eliminator - it will find spys that hide in your computer.
Also try this one: Bazooka Spyware Scanner - similar, but you have to delete yourself the malwares found - it will redirect you for help on their site.
Also try Ewido anti-malware 3.5 (you can find it for free); it will scan very thoroughly your computer.
Also try AboutBuster.exe - can be found for free
Also try Spywareterminator.exe (also free); it will install on your computer though (like Ewido too - the others are run each time you need them) - it found me some trojans ...
If some malwares can not be eliminated by the scanners that nevertheless found them, try these two softs: KillBox.exe and ATF Cleaner; both open windows that ask for the path of the malware you want to delete; as you already will know it from the scanners - they give the path of what they find, you just put it in their windows and will be able to delete the ****.
Also try Smitfraud.Fix.exe - you can find it for free (pay attention of what you decide to delete though)
and of course Hijackthis - similar as the previous one.
If you don't know what to delete put the infos from the logs these both softs create in a forum, maybe somebody will be able to help you.
And the last thing: avoid using Norton, especially the Spysweeper that comes with it - I had problems with them (even on Microsoft site it is written that they can cause problems - especially with windows explorer.exe).
Pay very much attention if you want to uninstall them (an inappropriate uninstallation will cause your computer to become instable) - Go to appropriate sites where it is explained how to uninstall this antivirus suite.