I get the following error when displaying the "categories" screen in the front end
Warning: mysql_fetch_array(): supplied argument is not a valid MySQL result resource in /var/www/html/nhmagDev/httpdocs/components/com_aardvertiser/aardvertiser.php on line 98
This seems to be because it's looking for any expiring ads to email the users, but there aren't any in my (test) setup, and the code doesn't check a "no result set" condition, hence the error I would guess.
It appears that changing line 98 to
while(!(!$result) && $rows = mysql_fetch_array($result))
does the trick…
Might just be a "quick'n'dirty" though :(
This issue is now fixed in the upcoming release