Description:
------------
dont run 

Reproduce code:
---------------
<?php
if(ereg("^([a-zA-Z0-9_-])*$", $_POST['account']) && ereg("^([a-zA-Z0-9_-])*$", $_POST['password']) && ereg("^([a-zA-Z0-9_-])*$", $_POST['password2']))
{
	if ($page="index.php" && $_POST['account'] && strlen($_POST['account'])<16 && strlen($_POST['account'])>3 && $_POST['password'] && $_POST['password2'] && $_POST['password']==$_POST['password2'])
	{	
		$check=mysql_query("select * from accounts where login='".$_POST['account']."'");
		$check1=mysql_num_rows($check);
		if($check1>0)
		{
			echo "<p clss='error'><b>Failed to register : an account already excist .</b></p>";
		}
		else
		{
	  		mysql_query("INSERT INTO accounts (login, password, access_level) VALUES ('".$_POST['account']."', '".base64_encode(pack('H*', sha1($_POST['password'])))."', 0)", $link);
  			mysql_close($link);
	 		print '<p class="error"><b>Registration over successful </b></p>';
		}
	}
	else
	{
  	print '<p class="error"><b> </b></p>'.mysql_error();
	}
}
else
{
	echo "Restrictions have not been tested for safety. Please try to sign up with another username and password.";
}
?>

Expected result:
----------------
Warning: mysql_num_rows(): supplied argument is not a valid MySQL result resource in \insert.php on line 7

Registration over successful


Actual result:
--------------
a