Are you running Firefox in Private Browsing - Use Firefox without saving history mode?

You need to update your plug-ins. It is important to keep them updated due to continuing security fixes and improvements in those plug-ins:

• Adobe PDF Plug-In For Firefox and Netscape "9.3.3"
• Next Generation Java Plug-in 1.6.0_20 for Mozilla browsers

1. Check your plugin versions: http://www.mozilla.com/en-US/plugincheck/
   • Note: plugin check page does not have information on all plugin versions
2. Update Adobe Reader (PDF plugin):
   • From within your existing Adobe Reader (if you have it already installed):
     • Open the Adobe Reader program from your Programs list
     • Click Help > Check for Updates
     • Follow the prompts for updating
     • If this method works for you, skip the "Download complete installer" section below and proceed to "After the installation" below
   • Download complete installer (if you do NOT have Adobe Reader installed):
     • Use Firefox to download and SAVE the installer to your hard drive from the link in the article below
     • On the Adobe page, un-check any extra items (i.e. Free McAfee® Security Scan Plus) then click Download button
     • If you see message just under tabs, DO NOT click the Allow button, instead click below that where it says "click here to download".
     • Click "Save to File"; save to your Desktop (so you can find it)
     • After download completes, close Firefox
     • Click the installer you just downloaded and allow the install to continue
       • Note: Vista and Win7 users may need to right-click the installer and choose "Run as Administrator"
     • Download link and more information: https://support.mozilla.com/en-US/kb/Using+the+Adobe+Reader+plugin+with+Firefox#Installing_and_updating_Adobe_Reader
   • After the installation, start Firefox and check your version again.
3. Update Java: https://support.mozilla.com/en-US/kb/Using+the+Java+plugin+with+Firefox

Java 6U21 is not a required update:

Bug Fixes Java SE 6 Update 21 does not contain any additional fixes for security vulnerabilities to its previous release, Java SE 6 Update 20. Users who have Java SE 6 Update 20 have the latest security fixes and do not need to upgrade to this release to be current on security fixes.