Error during startup after install

[Manuel B. Melguizo García <robotato500%gmail.com@localhost>]

Hello.
I've been trying to install NetBSD on an old HP mini 210 netbook. I have 
no issue during the install process, and NetBSD boots fine from the hard 
disk. However, during startup, I get the following errors:

warning: lookup /dev/console: error 22
exec /sbin/init: error 22
init: trying /sbin/oinit
exec /sbin/oinit: error 22
init: trying /sbin/init.bak
exec /sbin/init.bak: error 22
init: trying /rescue/init
exec /rescue/init: error 22

and I'm prompted to give a different init path or reboot.
So far I've gathered that the problem is most likely that the file 
system is inaccessible, but I don't understand why. I've tried 
reinstalling multiple times, both with the "use the entire disk" and the 
"delete everything" options (although always with MBR partitioning 
because this laptop still has a BIOS), and specifying the FFSv2ea, FFSv2 
and FFS file systems, always with the same result. I've also tried 
mounting the hard drive from the shell of the install image, but I get 
the error "incorrect super block".
I'd appreciate any possible help diagnosing this issue. Thanks in advance: