fwrite and fopen in cache system

[Philwn]

I am getting a rediculous amount of errors in the log on my host saying the following but for numerous referer addresses.

[Wed Sep 21 12:15:32 2011] [error] [client 85.189.254.101] PHP Warning:  fwrite(): supplied argument is not a valid stream resource in /home/sites/myurl.co.uk/public_html/Category.php on line 122, referer: http://www.myurl.co.uk/Category/En/Floats/

it is a simple cache system i use and it appears to work as when you view source at the bottom of the page is the comment about the file being cached and retrieved. My page code:

 

<?php 
   $cat = $_GET["cat"];
   $sub_cat = $_GET["sub"];
   $language = $_GET["lang"];
$cachefile = "cache/".$cat."-".$sub_cat."-".$language.".html";


      $cachetime = 60 * 60 * 400; // 5 days


      // Serve from the cache if it is younger than $cachetime

      if (file_exists($cachefile) && (time() - $cachetime
         < filemtime($cachefile))) 
      {

         include($cachefile);


         echo "<!-- Cached ".date('jS F Y H:i', filemtime($cachefile))." -->";


         exit;

      }

      ob_start(); // start the output buffer
include("./includes/db_con.inc.php");
$page_title = $cat . " - " . $sub_cat;
$sql_meta = mysql_query("SELECT * FROM sub_cat WHERE name='$sub_cat'");
$row_meta = mysql_fetch_assoc($sql_meta);
$meta_desc = $row_meta['META_DESC'];
$meta_key = $row_meta['META_KEY'];
include("./includes/head.php"); 
include("./includes/header.php");
mysql_free_result($sql_meta);
  ?>

<div id="main-page-header">
<?php 
$desc_sql = mysql_query("SELECT * FROM sub_cat WHERE name='$sub_cat'");
$row_desc = mysql_fetch_assoc($desc_sql);
$description = $row_desc['description'];
echo "<img src='$img_loc/product-pages/sub-cat-head/".str_replace(" ", "-", $row_desc['name'])."-sub-cat-head.jpg' width='940' height='310' />";
mysql_free_result($desc_sql);
?>
</div>

  <div id="page-content">
  
    <div id="main-page-text">
    
    <h1><?php echo $sub_cat; ?></h1>
<h2 class="crumbs"><a href="<?php echo "$url/Products/$lang/"; ?>">Products</a> > <a href="<?php echo "$url/Category/$lang/".urlencode($cat)."/"; ?>"><?php echo $cat; ?></a> > <?php echo $sub_cat; ?></h2>
<p>
<?php echo $description; ?>
</p>

  <script src="http://connect.facebook.net/en_US/all.js#xfbml=1"></script><fb:like layout="button_count" show_faces="false" width="170" font="verdana"></fb:like>

    
  <div id="related-wrap">
  
  <h2><?php echo $sub_cat; ?> Products</h2>
    
    <?php
$range_products = mysql_query("SELECT * FROM $table WHERE CATEGORY='$cat' AND SUB_CATEGORY='$sub_cat' AND display='1' ORDER BY sortID ASC");
while($row_range = mysql_fetch_array($range_products))
    { 
$prodid = str_replace("/", "-", $row_range['PRODID']);
$cat_link = urlencode($row_range['CATEGORY']);
$sub_cat_link = urlencode($row_range['SUB_CATEGORY']);
echo "<div class='related-products'>\n<a class='related-img' href='$url/Product/$lang/$cat_link/$sub_cat_link/$prodid/'>\n<img src='$img_loc/product-pages/Range-thmb/$prodid.jpg' width='120' height='120' /></a>\n";
    echo "<h5>" . $row_range['PROD_TITLE'] . "</h5>\n";
    echo "</div>\n";
}
mysql_free_result($range_products);
?>

    </div>    
    
     <div id="FAQ-wrap"><h2>Frequently Asked Questions</h2>
  <?php
  $QA_table = $lang . "_qanda";
  if ($id=="") {
      $list_QA = mysql_query("SELECT * FROM $QA_table WHERE SUB_CATEGORY='$sub_cat' AND DISPLAY='1'") or die();
  }
  else {
  $list_QA = mysql_query("SELECT * FROM $QA_table WHERE PRODID='$id' AND DISPLAY='1'") or die();
	}
  while($row_QA = mysql_fetch_array($list_QA))
{ 
  echo "<div id='FAQ-QA'>";
  echo "<h2 class='FAQ-question'>Q: ".$row_QA['QUESTION']."</h2>";
     echo "<p class='FAQ-question'>A: ".$row_QA['ANSWER']."</p></div>";
}
mysql_free_result($list_QA);
  ?> 
    <div id="FAQ-question">
        <h2 class="white">Got a question about the 
        
        <span class="got-question-product"><?php echo $sub_cat; ?></span> 
        
        </h2>  
      </div>
      
      </div>

    

    </div>


    
    <div id="totem-menu-container"><?php include("./includes/search.php") ?>
    
    <?php include("./includes/totem.php") ?>
    
    </div>
  
  </div>
  </div>
<!-- MAIN CONTENT OF PAGE BELOW HERE -->

<!-- END MAIN CONTENT OF PAGE BELOW HERE -->

  
  
  
<?php include("./footer.php") ?>

<?php
       // open the cache file for writing
       $fp = fopen($cachefile, 'w'); 


       // save the contents of output buffer to the file
    fwrite($fp, ob_get_contents());

	// close the file

        fclose($fp); 

	// Send the output to the browser
        ob_end_flush(); 
?>
   
   
   

[WebStyles]

kind of off-topic, but how is

$cachetime = 60 * 60 * 400; // 5 days

equal to five days?

[Philwn]

it was 60 * 60 *120 which was five days I have increased it and not chnage the comment