There is little point in restoring the files, if avast still considers them infected the act of moving them out of the chest will cause the file system shield to alert again. So you will be in a cycle.
What is the infected file name, where was it found, malware name e.g. (C:\windows\system32\infected-file-name.xxx, malware name) ?
For detection on on demand scans, check C:\Documents And Settings\All Users\Application Data\Alwil Software\Avast5\Log (Windows 2000, Windows XP). Or C:\ProgramData\Alwil Software\Avast5\log (windows Vista, windows 7).
As Pondus asks, why would you want to do this ?
