OpenBSD does not shutdown gracefully

If you re-installed your OpenBSD system, or compiled your own kernel, and find that it does not shutdown gracefully from the console server or Portal, you may need to disable "mpbios" in the kernel.

This is detailed in another article (while solving a different problem). Please see the following:

http://support.arpnetworks.com/kb/vps/openbsd-hangs-at-setting-tty-...