Really weird filesystem behavior on prep

I'm trying to upgrade my prep box to the latest 3.0 RC1 binary build,
and I noticed something.

I booted the kernel with the 2.0.2 userland still intact. This worked.

I noticed some different stuff, so I wanted to pull the kernel configs
from the 2.0.2 kernel and the 3.0 RC1 kernel and compare them. So I
used this command straight from the options man page:

strings netbsd | sed -n 's/^_CFG_//p' | unvis

Except I redirected that to a file:

strings netbsd | sed -n 's/^_CFG_//p' | unvis > /root/kernconf.2.0.2

Now, for the weird part.

The directory that I redirected the file into suddenly behaves as if
it has no files in it. That is, ls shows nothing:

root@bugs:/root # ls /root
root@bugs:/root #

If I reboot, it comes back.

What? How can this be happening?

Any advice would be appreciated.

Thanks.

Andy