I've just replaced an existing Linux installation with a NetBSD
one with install disks boot1.fs and boot2.fs taken from the website
as of about 2 weeks ago.  Upon rebooting my BIOS informed me I had
a "bad partition table" and halted.  NetBSD installs itself in the
4th partition but apparently in some circumstances doesn't bother
marking that as bootable - my prior Linux installation booted from
the 1st partition I think.   If I were new to NetBSD coming from 
Linux this would be a poor introduction IMO.

I've had a similar experience before - installing NetBSD over
a prior NetBSD-with-RAID installation confused the new installation
into thinking it was RAID-capable, when it wasn't, rendering it
unbootable too.  [I sent mail last August about this.]  The
partition table initialization code in the installer probably
needs a bit of work.

Neil.