There are many ways that cookies can get cleared between Firefox sessions. These include: * Having Firefox set to store cookies only for the current session, or not to store cookies at all, and not having an exception for Ancestry * Having Firefox set to clear cookies at shutdown * Using Private Browsing mode * Using add-ons that modify cookie handling * Using external privacy or utility software that clean up browser data It's also possible for your existing Ancestry cookies to have become corrupted, so let's start by clearing them. Next time you visit the site, before logging in (or now, if you like), open the Cookies dialog using any of these: * right-click and choose View Page Info > Security > "View Cookies" * (menu bar) Tools > Page Info > Security > "View Cookies" * click the padlock or globe icon in the address bar > More Information > "View Cookies" In the dialog that opens, ancestry.com should be pre-filled at the top so you can remove the site's cookies individually and close the Cookies dialog. Then click the Permissions icon at the top of the Page Info dialog and see what the "effective" permission is for Ancestry under "Set Cookies". Assuming the "Use default" checkbox is checked, the effective permission should show in gray. If it is not "Allow" then uncheck the box and click the Allow button. Does that make any difference the next time?