The only thing that got rid of the Trojan StartPage.1 was from www.NoAdware.net it will cost you $35 but if it dosn't work then they will give you your money back. I'm sure it will work for you.
But start with downloading some free software and try that first eventually building up to some you have to pay for.
On my system I have Antivir, Spybot Search and Destroy, Diamond CS TDS3, Spyware Blaster and NoAdware.
All available through Google, most were free downloads others were ($8) and ($35). All have their own strengths and weaknesses.
All the sites I have listed are trustworthy so no worries about saying yes. Dont bother with Norton it does not work very well and says the system is free when it is still infected.
Remember to Turn off System restore first though.
Its under My Computer (right click) Propertied...System Restore....Check the Turn off box.
Turn it on whe all is well and you are free of Trojans and Viruses
Bob the Builder