Disable Extension Compatibility Checking in Firefox 3

• Type about:config into Firefox's address bar and click the "I'll be careful, I promise!" button.
• Right-click anywhere. Choose New>Boolean. Name the new config value extensions.checkCompatibility and set it to false.
• Right-click anywhere and choose New>Boolean again. Name this new boolean pair extensions.checkUpdateSecurity and set the value to false.
• Right-click anywhere. Choose New>Boolean. Name the new config value extensions.checkCompatibility.VERSION and set it to false. 
• e.g. extensions.checkCompatibility.3.6
• Note the capital C in checkCompatibility - it's important.
• VERSION is the version number of firefox, e.g. 3.6
• If using an Alpha version, the version number would be VERSIONa, e.g. 3.6a
• If using a Beta version, the version number would be VERSIONb, e.g. 3.6b 
• Restart Firefox.