This is weird: I can ssh into a box, but I can't access it directly

["James H. H. Lampert" <jamesl@touchtonecorp.com>]

One of our Linux boxes is behaving oddly. If I ssh into it, I can 
connect easily, and I get:
> The programs included with the Debian GNU/Linux system are free software;
> the exact distribution terms for each program are described in the
> individual files in /usr/share/doc/*/copyright.
>
> Debian GNU/Linux comes with ABSOLUTELY NO WARRANTY, to the extent
> permitted by applicable law.
> Last login: Wed Jan 29 08:32:12 2020 from 192.168.1.15

But if I go into the server cage, and punch it up on the KVM switch, and 
try to sign on as root, I get:
> Debian GNU/Linux 8 Titan tty1
>
> Titan login: root
> [10371235.533392] end_request: I/O error, dev sda, sector 105228592

and after a few seconds, the screen clears, and goes back to
> Debian GNU/Linux 8 Titan tty1
>
> Titan login:

Or, at other times, when I punch it up on the KVM switch, I get a whole 
screen full of hard disk error messages.

It's pretty clear to me that the box is more-or-less shot anyway (even 
from the ssh session, if I try to "cd home," I get an error message), 
but can somebody tell me why I'm getting one behavior through ssh, and 
completely different behavior through a direct connection?

--
JHHL