Buildkernel fails after cvsup and buildworld today (5.0 -> 5.1) any help?

[BSDVault]

I currently still booted into 5.0-RELEASE-p7.  My hardware is an asus
A7M-266D dual AMD MP-1800's .  I have two Western Digital 120Gig drives
(IDE) and 2 512 PC-2100 DDR.

Buildworld completed fine after cd /usr/obj; chflags -R noschg * ; rm -rf *.
I then tried to buildkernel as I always have and got the following error:

machdep.o: In function `cpu_idle':
machdep.o(.text+0x14a7): undefined reference to `sched_runnable'
*** Error code 1