older zabbix installations, when upgraded, can have incorrect data in the db. 1.8 fails on too many cases of those.

1. undefined index in user profile if referencing incorrect mediatype in media table;
2. Undefined index: 10032[/srv/www/htdocs/zabbix-1.8/include/maps.inc.php:321] - if referencing non-existent hostid in a host map element;
3. can't edit map if referencing non-existent triggerid for a map link indicator