Reboots when /proc is mounted

[Sad Clouds <cryintothebluesky%googlemail.com@localhost>]

dell$ uname -a
NetBSD dell 5.0_STABLE NetBSD 5.0_STABLE (GENERIC) #1: Sat Jan 23 15:05:16 GMT 
2010  root@p3smp:/opt/obj.amd64/sys/arch/amd64/compile/GENERIC amd64

On this machine when I try building lang/mono and /proc is mounted, the 
machine gets rebooted. It looks like this package triggers a bug, because when 
I umount /proc and try building the same package, everything works fine.

I think I've seen this problem before some time ago. I'll try to get a crash 
dump and get a back trace when I have some time.

Has anyone seen this before and knows where the problem is?