Upon reboot of a stock 1.5.2 installation on an IBM eServer x220, I always
get the following error: 
savecore: /netbsd: kvm_dump_mkheader: Pread: Invalid argument

(and indeed typing savecore /var/crash gives the same thing). I'm guessing
that it's finding something in swap that looks like a kernel dump. It
looks to be very similar to kern/15502. I don't think it's a serious
problem, but this is a customer's machine and they might not be happy
about errors at boot time :-)

I can provide dmesg upon request.

-- 
Stephen