The error is:

Warning: mysql_num_rows(): supplied argument is not a valid MySQL result resource

The offending code snippet essentially looks like this:

$result = mysql_query(“$query_STRING” );
if (mysql_num_rows($result) > 0)
{

which then continues on…

Note that $query_STRING is a string variable that contains the mySQL query.

The problem with this error message is that it is typically due to a problem in the query itself, and there can be many causes.  To catch the cause, change the line that performs the query to:

$result = mysql_query(“$query_STRING” ) or die(mysql_error());

The statement die(mysql_error()) will catch the true error and with luck give you a more meaningful error message.