'''1.''' only the xxxx.default extension : [https://support.mozilla.com/en-US/kb/Backing%20up%20your%20information#w_backing-up-your-profile Backing up your profile] see also: [https://support.mozilla.com/en-US/kb/Profiles Profiles] [http://support.mozilla.com/en-US/kb/Managing-profiles Managing profiles] [https://support.mozilla.com/en-US/kb/Recovering%20important%20data%20from%20an%20old%20profile Recovering important data from an old profile] '''2. '''no reason to backing up Documents and Settings\Local Service\Application Data\Mozilla..... "The LocalService and NetworkService profiles are automatically created by Windows XP for two new built in user accounts that are used by the Service Control Manager to host services that do not need to run as the local system account." from : http://technet.microsoft.com/en-us/library/bb490855.aspx thank you Please mark "Solved" the answer that really solve the problem, to help others with a similar problem.