[Sew_Sumi]

The gamemode is still compiled with the IRC plugin included, so even though you aren't running it, the script is still looking for it... Fix that, and it may run fine... However, the IRC plugin alone shouldn't stop the server, so I suspect you're missing other portions, via either deleting them, or by you simply trying to do something in a way that you shouldn't.

If the MySQL plugin can't connect or get the data it needs, that'll sometimes cause the unknown gamemode output.

You need to not just not run the plugin, you need to disable the IRC portion of the script you have.