We have a mistake in the source code:
include/hosts.inc.php:
// delete screen items
DBexecute('DELETE FROM screens_items WHERE '.DBcondition('resourceid',$hostids)).' AND resourcetype='.SCREEN_RESOURCE_HOST_TRIGGERS;

It calls this query:
Time:0.000515 SQL: DELETE FROM screens_items WHERE (resourceid IN (89))

The last round bracket should be after SCREEN_RESOURCE_HOST_TRIGGERS!