[SOLVED] mysql_num_rows error

[AsiaUnderworld]

I've moved my code to a new server, and ive now got these errors

 

Warning mysql_num_rows(): supplied argument is not a valid MySQL result resource in /home/niccaman/public_html/checkuser.php on line 42

 

Warning mysql_num_rows(): supplied argument is not a valid MySQL result resource in /home/niccaman/public_html/checkuser.php on line 42

 

Warning mysql_num_rows(): supplied argument is not a valid MySQL result resource in /home/niccaman/public_html/checkuser.php on line 57

 

Warning mysql_num_rows(): supplied argument is not a valid MySQL result resource in /home/niccaman/public_html/checkuser.php on line 57

 

Warning cannot modify header information - headers already sent by (output started at /home/niccaman/public_html/checkuser.php:42) in home/niccaman/public_html/checkuser.php on line 24

 

 

Whats up with this?

 

Here are the lines around 42:

 

37  global $con;

38  $q = "SELECT ID FROM userinfo WHERE username = '$user'";

39  $result = mysql_query($q, $con);

40  $result = mysql_fetch_array($result) o die ('error: ' .mysql_error());

41  $i = 0;

42  while ($i <= mysql_num_rows($result))

43  {

44    $r = $r . $result[$i];

45  $i++;

46  }

47

48  return $r;

49  }

 

 

help would be great