C:\Program Files\Britannica 2003\Deluxe EditionCD\data\eb\gist-5.jar\52738\0.gz
C:\Program Files\Britannica 2003\Deluxe EditionCD\data\eb\articles-1.jar\119575\47421.gz

look at file name, JAR archive is renamed ZIP archive, so you may open it in WinZip/WinRar/Total Commander/… and extract 0.gz file in \52738 folder and send it to virus@avast.com with subject something like “false alarm” because it seems it is. Thanks !