Don't worry! In most cases you can easily fix this issue. Do the following:

1. Refresh the page by pressing Ctrl+F5 on your keyboard
2. Make sure you have the latest version of Adobe Flash Player installed. You can download it here
3. Clear your browser's temporary data (cache). Learn how to do this here
4. Upgrade your browser to the latest version or try another browser:
   • Amigo
   • Opera
   • Mozilla Firefox
   • Google Chrome
   • Internet Explorer

All done! After you do this and open your discussions again, everything will be OK!