Stocker360, I run avast! as well and the pagefile.sys is locked file by Windows and thus can not be scanned:
http://forum.avast.com/index.php?topic=36028.0
Any file would be detected before it was able to get into pagefile.sys and either deleted or sent to the quarantine Chest depending on your choice.
If you have the Hibernate function active then the hiberfile.sys file would also not be able to be scanned.