Cannot do anything with a "locked as read-only" file

Hi:

We have some files which are "locked as read-only" and checked out by a user (not sys. account). I am primary site collection admin, but I cannot do anything with it: could not discard the check out, override check in, delete nor undeclare record. All ends up in a message like "cannot be updated because it is locked as read-only" (The undeclare record does nothing).

I have tried to use the Designer & fix options in Record Declaration Settings as suggested in forums and webs without succeed.

Just wonder if there is any other method to deal with -or- is it simply a bug in SP 2010?

Thanks