sub DBI::db::STORABLE_freeze {
   my ($self, $cloning) = @_;
   return if $cloning;

   return "Lost DBI ref $self";
}

##</code><code>##

Unexpected object type (4) in store_hook() at blib/lib/Storable.pm 
   (autosplit into blib/lib/auto/Storable/_freeze.al) line 234, 
   at script-name.pl line 58

##</code><code>##

return freeze("string");     # probably 'cause it's not a ref

my $$msg = "string";
return freeze($msg);         # still no-go