Backup your personal data (to find out how see this page -
http://www.malwaresolutions.com/how-to-backup_ files.html)
The first thing you will need is anti-virus software! Download, install and update AVG Anti-Virus - it's free and can be found here - You might need to get it on to a flashdrive or CD using another computer if you are having trouble downloading it directly -
http://www.malwaresolutions.com/antivirus-soft ware.html
It's easy to install and use - to read about how to install AVG go here -
http://www.malwaresolutions.com/how-to-install -avg-antivirus.html
Then start the computer is Safe Mode - (usually this is accomplished by tapping the F8 key on your keyboard while the computer is starting up) - read more about starting a computer in Safe Mode here -
http://www.malwaresolutions/how-to-start-in-sa fe-mode.html
Then run AVG and do a full system scan, let it find and remove any viruses it finds.
One other thing too, if you are running Windows XP, you should also remove your System Restore files. Viruses love to hide in them. To learn how to temporarily disable System Restore see this page -
http://www.malwaresolutions.com/disabling_syst em_restore.html
You might want to try using MSCONFIG as a tool
http://www.malwaresolutions.com/how-to-use-msc onfig.html