This came up before - http://comments.gmane.org/gmane.os.openbsd.misc/214708
I don't know what nexcom are like but I wonder if it might be worth attempting to talk to their support people. Perhaps their BIOS vendor has new code that they could update to. If I understand one of the posts correctly, it might also be worth trying to use grub 2 as the main boot-loader (chaining to OpenBSD's) as a work around.
