There maybe a problem with the SQL query for the access version, the SQL server version I have been using seems to be OK.
Change SQL query around lines 376 to 379 of the file functions_common.asp to the following query:-
strSQL = "SELECT " & strDbTable & "Permissions.* "
strSQL = strSQL & "FROM " & strDbTable & "Permissions "
strSQL = strSQL & "WHERE (" & strDbTable & "Permissions.Group_ID = " & intGroupID & " OR " & strDbTable & "Permissions.Author_ID = " & lngLoggedInUserID & ") AND " & strDbTable & "Permissions.Forum_ID = " & intForumID & " "
strSQL = strSQL & "ORDER BY " & strDbTable & "Permissions.Author_ID DESC;"