So all of a sudden, after a week of using it, I get an error message on my zabbix server gui (http://localhost/zabbix/.)
The error says: Zabbix serve
Looks like the problem was that I created a Database monitoring Item programmatically and it triggered a bug that caused the server to shutdown.
Once I deleted the item the server came back up, and creating subsequent Items didn't kill it.
The deadly Item had a value_type of Numeric unsigned, -1 programmatically, while the newly created Items have a value_type of float, which is 0 programmatically.
The whole thing has a voodoo element to it but it did solve my problem.