Computer is working fine but some unknown files remain.. what should i do?

I was surfing some guitar tabs websites a few days back when norton antivirus%26windows defender started to show danger signs.In panic,saw the defender say restart your computer and so I did.When the windows started again,I couldn't open anythin%26a message kept on popping

'Windows explorer is not working'

脟heck the web for solution and restart the program'

or

'Restart the program'

That time as I didn't have any antispyware program%26couldn't do anythin on the computer,someone told me to recover to an earlier date.So i did%26it worked.The computer had started working properly again.

After that now AVG free edition,Ad-Ware,Spybot,Norton Antivirus%26the Vista's Windows Defender...none of these show any sign of virus or adware/spyware.But my concern is I see some strange links n files around. Forexample there are 2 icons for www.asecurityboard.com on the desktop and found using startup manager that there is a 'launcher.exe'file set to operate on startup.

What exactly should I do now?

Computer is working fine but some unknown files remain.. what should i do?ktm

For an all-in-one, comprehensive, free scan of your computer, try this:

http://www.bitdefender.com/scan8/ie.html

Computer is working fine but some unknown files remain.. what should i do?nortan