Need help with error

Using Postgres 7.0 on BSDI 4.1

For the last several days we are getting errors that look like this:

Error: cannot write block 0 of krftmp4 [adm] blind.

An interesting thing is that in this example, krftmp4 is a table that
the user that got this error message would not have accessed in any
way. The user was trying to do an update of a different table in the
adm database. When this happens, it seems that the backend dies, which
ends up causing the backend connections for all users to die.

Can someone give me an idea of what this error message means, and
perhaps how to fix it?

I haven't been keeping up with the list lately, so please forgive me
if this has been covered recently.

Thanks.