There is still too little to even take a stab at it.
Please try to give detailed answers this helps us.
How do you know you are infected - e.g. what was it called on your friends system ?
What detected it ? and when/how - what detected it on his system ?
What was the file name, where was it found example (C:\windows\system32\infected-file-name.xxx)?
This would at least allow for a google search on the infected/suspect file name and see if there is any known virus associated with it.
If you haven't already got this software (freeware), download, install, update and run it,
Ewido Security Suite. It would probably be best to run it from safe mode. Once you have done that schedule a boot-time scan from within avast.
You could also try an on-line virus scanner.
Virus Scanners and other useful Links
Security-Ops.eu.tt