To get offline mode to work, you have to have 'remember password' checked, and you have to log into Steam at least once successfully once it's checked. Why? Hell if I know. Talk to Valve.The reason for this is the "remember password" option implies that anyone who uses your computer is free to use your Steam account. If this is *not* checked, then Steam will not allow others to use your account, online or not. Because there is no way to "authorize" a user offline, Valve could have either allowed everyone to use your account offline, or no one. Because leaving the "remember password" option unchecked implies you do not want everyone at the computer to be able to access your account, it makes sense to allow no one to do so.