If there is more to the message than what you have posted, that additional information might be helpful in leading you to the exact cause; for example:

• "Script: chrome://fastdial/content/storage.js:71"

See: http://kb.mozillazine.org/Unresponsive_Script_Warning

The information submitted with your question indicates that you have out of date plugins with known security and stability issues that should be updated. To see the plugins submitted with your question, click "More system details..." to the right of your original question post.

• Shockwave Flash 10.1 r82
• Java Plug-in 1.6.0_02 for Netscape Navigator (DLL Helper)
  • Very old version
  • Remove before installing new version (link to removal instructions below)

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 the Flash plugin to the latest version.
   • Download and SAVE to your Desktop so you can find the installer later
   • If you do not have the current version, click on the "Player Download Center" link on the "Download..." page below
   • After download is complete, exit Firefox
   • Click on the installer you just downloaded and install
     • Windows 7 and Vista: may need to right-click the installer and choose "Run as Administrator"
   • Start Firefox and check your version again or test the installation by going back to the download link below
   • Download and information: http://www.adobe.com/software/flash/about/
     • Use Firefox to go to the above site to update the Firefox plugin (will also install plugin for most other browsers; except IE)
     • Use IE to go to the above site to update the IE ActiveX
3. Update the Java plugin to the latest version.
   • Download site: http://java.sun.com/javase/downloads/index.jsp (Java Platform: Download JRE)
   • Also see "Manual Update" in this article: http://support.mozilla.com/en-US/kb/Using+the+Java+plugin+with+Firefox#Updates
   • Removing old versions (if needed): http://www.java.com/en/download/faq/remove_olderversions.xml
   • Remove multiple Java Console extensions (if needed): http://kb.mozillazine.org
   • Java Test: http://www.java.com/en/download/help/testvm.xml

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

• Don't make any changes on the Safe mode start window.

See

• Troubleshoot extensions, themes and hardware acceleration issues to solve common Firefox problems
• Troubleshoot issues with plugins like Flash or Java to fix common Firefox problems

A possible cause of a slow start is security software (firewall) that blocks or restricts Firefox without informing you about that, possibly after detecting changes (update) to the Firefox program.

Remove all rules for Firefox from the permissions list in the firewall and let your firewall ask again for permission to get full unrestricted access to internet for Firefox and the plugin-container process.

See:

• Server Not Found - Troubleshoot connection problems
• Configure firewalls so that Firefox can access the Internet