You may have installed an extension that adds this feature.

Start Firefox in Diagnose Firefox issues using Troubleshoot Mode to check if one of the extensions is causing the problem (switch to the DEFAULT theme: Firefox (Tools) > Add-ons > Appearance/Themes).

• Don't make any changes on the Safe mode start window.
• https://support.mozilla.com/kb/Safe+Mode

• https://support.mozilla.com/kb/Troubleshooting+extensions+and+themes

Hi Cor-el

The problem was active before any add-ons or extensions were added. To be certain I deleted all the add-ons from V4 but the issue was still there. I have re-installed v4 now as the issue was a pain.

Did you try if it still happens in Save mode ?

• https://support.mozilla.com/kb/Safe+Mode

I also have this problem. Fine in 3.6 not in 5, (unsure about 4).

Still happens in safe mode.

I have the issue around pdf's is there a way I can change the <a> tag to stop firefox from prefetching it?

If I view source as the request then I get something like this, although starts a slightly different point each time.

charset="utf-8" />
<style type="text/css">
@page {
 size: A4 landscape;
 margin: 0;
}

body {
 font-size: 3mm;
 line-height: 4mm;
 size: landscape;
 padding: 0;
 margin: 0;
}

.backer {
 background: #fff;
}

.tip_layout {
 font-family: Arial, sans-serif;
 padding: 1cm 1cm 0;
 page-break-after: always;
}

.tip_layout table {
 border-collapse: collapse;
 font-family: Arial, sans-serif;
 margin: 0;
 overflow: hidden;
 padding: 0;
 page-break-after: always;
}.tip_hole {
 background: #fff;
 border: none;
 height: 60mm;
 margin: 0;
 overflow: hidden;
 padding: 1mm;
 position: relative;
 width: 67mm;
}

.tip_title,
.details_custom {
 border-top: .5mm solid #0096db;
}

.tip_title {
 color: #0096db;
 display: block;
 font-size: 3.35mm;
 line-height: 4mm;
 margin: 0;
 padding: .8mm 0;
 text-transform: uppercase;
}

.modal_content .tip_title {
 margin-right: 10px;
}

.tip_hole ul,
.tip_hole ol {
 margin: 0 0 0 2mm;
 padding: 0;
 position: relative;
}
.checkboxLists ul {
 margin-left: 3mm;
}

.tip_hole ol {
 margin-left: 4.5mm;
}

.tip_hole ul ul,
.tip_hole ul ol,
.tip_hole ol ul,
.tip_hole ol ol {
 margin-bottom: 0;
}

.tip_hole li {
 font-size: 3mm;
 display: list-item;
 line-height: 4mm;
 list-style: none;
 margin-left: 0;
}
 .tip_hole ul li:before {
  content: '›';
  left: -2mm;
  position: absolute;
  top: auto;
 }
 .tip_hole .checkboxLists ul li:before {
  border: .2mm solid #000;
  content: ' ';
  display: block;
  left: -3mm;
  margin-top: 1mm;
  height: 1.8mm;
  width: 1.8mm;
 }

.tip_hole ol li {
 list-style: decimal;
}
.tip_hole ol ol li {
 list-style: lower-latin;
}
 .tip_hole ol li:before {
  content: '';
 }

.tip_hole p {
 font-size: 3mm;
 line-height: 4mm;
 margin: 0;
 position: relative;
}

.tip_hole img {
 display: block;
 height: 35mm;
}

.tip_hole .brand,
.tip_hole .customLogo {
 height: auto;
 position: absolute;
 right: 1mm;
 top: 1.3mm;
 z-index: 1;
}

.tip_hole .brand {
 height: 15.3mm;
 left: 0;
 top: 1mm;
 width: 67mm;
}

.lte8 .tip_hole .brand {
 width: 64mm;
}

.tip_hole .customLogo {
 width: 20mm;
}

.tip_hole .tipBackground {
 height: auto;
 left: 1mm;
 position: absolute;
 width: 67mm;
}

.tip_hole h2 {
 color: #0096db;
 font-size: 4.25mm;
 line-height: 4.5mm;
 margin: 11mm 22mm 6mm 0;
 padding: 0;
 position: relative;
}

.details_acc h2 {
 background: #0096db;
 color: #fff;
 font-weight: normal;
 margin: 0 0 3mm;
 min-height: 9mm;
 padding: 5mm 24mm 6mm 6mm;
}

.tip_hole .details_pad {
 margin-right: 22mm;
}

.tip_content_print_padded {
 padding-left: 6mm;
}

.tip_hole table {
 border-spacing: 0;
 font-size: 3mm;
 line-height: 4mm;
 margin: 0;
 width: 100%;
}
 .tip_hole table tr{
  height: auto;
 }
 .tip_hole tbody tr.odd {
  background: #f7f8fa;
 }
 .tip_hole th,
 .tip_hole td {
  border-left: .1mm solid #dadfe5;
  padding: 0 1mm;
  vertical-align: top;
 }
 .tip_hole th:first-child,
 .tip_hole td:first-child {
  border-left: none;
  padding-left: 0;
 }
 .tip_hole th {
  text-align: left;
 }
 .tip_hole th.p,
 .tip_hole td.p {
  margin-bottom: 0;
 }
</style>
</head>
 <body>
  <div class="backer">
  
    
     <div class="tip_layout">
      <table cellspacing="0">
       <tr>
       
        <td class="">
         <div class="tip_hole">
         
          
           
 
 
  <div class="tip_content_print details_custom">
   
   
 

 <div class="details_pad">
  <p>This resource contains important information for your workplace. Keep the information handy.</p>
 </div>

</div>

          
         
         </div>
        </td>
        
       
        <td class="">
         <div class="tip_hole">
         
         </div>
        </td>
        
       
        <td class="">
         <div class="tip_hole">
         
         </div>
        </td>
        
       
        <td class="">
         <div class="tip_hole">
         
          
           
 <div class="tip_title">Back of forearm stretch</div>
<div class="tip_content_print">
 
  
   <img alt="stretch" class="block" src="http://112.109.69.42/assets/Uploads/backofforearmstretch.jpg"/>
  
 
 <ul><li>Relax shoulders, elbow bent, bend wrist with palm facing down.</li>

<li>Hold hand and gently straighten elbow, stretching fingers back and down.</li>
</ul>
 
</div>

          
         
         </div>
        </td>
        
         
          </tr>
          <tr>
         
        
       
        <td class="">
         <div class="tip_hole">
         
         </div>
        </td>
        
       
        <td class="">
         <div class="tip_hole">
         
         </div>
        </td>
        
       
        <td class="">
         <div class="tip_hole">
         
         </div>
        </td>
        
       
        <td class="">
         <div class="tip_hole">
         
         </div>
        </td>
        
         
          </tr>
          <tr>
         
        
       
        <td class="">
         <div class="tip_hole">
         
         </div>
        </td>
        
       
        <td class="">
         <div class="tip_hole">
         
         </div>
        </td>
        
       
        <td class="">
         <div class="tip_hole">
         
         </div>
        </td>
        
       
        <td class="">
         <div class="tip_hole">
         
         </div>
        </td>
        
         
        
       
       </tr>
      </table>
     </div>
    
  
  </div>
 </body>

</html>HTTP/1.1 200 OK
Date: Wed, 29 Jun 2011 05:18:52 GMT
Server: Apache/2.2.16 (Debian)
X-Powered-By: PHP/5.3.3-7+squeeze1
Expires: Thu, 19 Nov 1981 08:52:00 GMT
Cache-Control: no-store, no-cache, must-revalidate, post-check=0, pre-check=0
Pragma: no-cache
Set-Cookie: bypassStaticCache=deleted; expires=Tue, 29-Jun-2010 05:18:51 GMT; path=/; httponly
Set-Cookie: bypassStaticCache=deleted; expires=Tue, 29-Jun-2010 05:18:51 GMT; path=/; httponly
Vary: Accept-Encoding
Content-Encoding: gzip
Content-Length: 2911
Keep-Alive: timeout=15, max=93
Connection: Keep-Alive
Content-Type: text/html; charset="utf-8"

If I tamper data the request this is what I get:

I've just installed Google's mod_pagespeed on the server and it seems to have fixed the problem. Unsure why?

I have returned to v4 as that works OK. I can't be bothered to fiddle with the thing, if Mozilla want their software to be used it should be robust before they launch it. I had more that enough years ago with Microsoft launching software that needed fixing, I now take the attitude if they want me to use something, fix it. If Mozilla want business' to use the software they need to thoroughly test it before launching it, I have no time or patience these days to play around with someone elses problem, sorry. Google Chrome, here we come.

Google mod_pagespeed has not solved the issue. I take the previous comment back.

Well it's seems to be reliable but not perfect.

Also note that it only happens if you click on a link not if you type the link's address into the address bar.