There are numerous popup blockers on the market, the most common two are described below.  You will need to disable popups for www.4x4earth.com.au to allow you to upload track files.  

For help on disabling popups for products not mentioned below, try here.

Internet Explorer 7 - Microsoft Windows XP SP2

When you install the Windows XP Service Pack 2 (SP2), Pop-up Blocker is automatically turned on in Internet Explorer and set to the medium setting, which means that it will block most automatic pop-ups. To allow pop-ups from 4x4earth.com.au:

• Launch an Internet Explorer browser window.
• In the Tools toolbar menu, point to Pop-up Blocker, and then click Pop-up Blocker Settings.

• Type http://www.4x4earth.com.au in the Address of Web site to allow box, and then click Add. Click the Close button to exit.

 Firefox

If you try to upload a track file as part of a track review submission, you may see an information bar which is a pale yellow bar just above the web page content and below the toolbars. This bar may warn you that a pop-up has been blocked. 

 Click on this bar and choose Allow popups for www.4x4earth.com.au to configure Firefox to allow pop-ups

Because the initial popup was blocked, you will now need to go into 'My Tracks' (link in the login box), and re-submit.  Because popups are no longer blocked you will get a popup asking for the track file location.