If you're using a local copy of Firefox, you may wish to just copy your local Firefox settings right into Firefox Portable. Your local Firefox profile is usually installed in C:\Documents and Settings\[user]\Application Data\Mozilla\Firefox\Profiles\default.???\ Just copy all of those files except the cache directories to the profile directory within Firefox Portable. When you start Firefox Portable for the first time, be sure to turn off disk cache, password saving and history if you're using a non-hard drive portable device. You can set all of these within the Privacy tab of the Firefox Options window. Sometimes, certain profiles will cause the launcher to fail or hang. This is usually due to an incompatible extension.