Our system was briefly in the future due to a clock problem. Now I see some triggers with "host unreachable" hanging, due in Aug 2013 and I can't remove them. I already did the following things:

update triggers set lastchange = unix_timestamp() where lastchange > unix_timestamp();
update items set lastclock = unix_timestamp() where lastclock > unix_timestamp();

I'm a bit lost because this currently renders zabbix unusable.