Cool Archive is giving a server error when you do an order by on title or reputation without supplying a username.
Current code:
  44: my $user = $query->param("cooluser");
  45: if ($user) {
  46:    my $U = getNode($user, 'user');
  47:    return $str . "<br>Sorry, no '$user' is found on the system!" unless $U;
  48: 
  49:    if ($useraction eq "cooled") {
  50:      $wherestr .= " and cooledby_user=".getId($U);
  51:    } elsif ($useraction eq 'written') {
  52:      $wherestr .= " and author_user=".getId($U);
  53:    }
  54: }
If we put in another if clause to check for this condition, then it should be fixed:
  54: } elsif ( $orderby =~ /title|reputation/ ) {
  55:	 return $str . "<br>A username must be supplied if ordering by title or reputation!";
  56: }

I've not tested this code, but I think it should do the job

N-Wing says: done; Cool Archive; I made the regex a bit more specific, though, I'm picky like that :)