Hier fehlt ein bisschen was:
AND t1.sponsor != '.$_SESSION['uid'].PHP-Code:
$fbanner = db_query ('SELECT t1.*
FROM '.$db_prefix.'_gebuchte_werbung t1
LEFT JOIN '.$db_prefix.'_reloads t2
ON (t1.tan = t2.tan AND (t2.uid = '.$_SESSION['uid'].' OR t2.ip = "'.$ip.'") AND t2.bis >= '.time().')
WHERE t2.tan IS NULL AND t1.werbeart = "forcedbanner" AND t1.menge > 0 AND t1.status = 1 AND t1.verdienst > 0 AND t1.sponsor != '.$_SESSION['uid'].
while ($f_banner = mysql_fetch_assoc ($fbanner)){
danach müsste das noch weitergehen...
Lad am besten noch mal die Originale hoch.