What is the "Bind to IP address" option when I log in?
When you log in to InsaneJournal, your browser writes a cookie to your computer that keeps track of certain information, so that you don't have to keep logging in on every page. The "Bind to IP address" option stores your IP address in the session information for your cookie, so that your cookie only works with that specified address.
Please note that this option does not stop you from logging in to InsaneJournal from another computer, but is merely a deterrent to account "hijacking". You can, however, choose to end all currently logged in sessions by using the "Expire all my sessions" option on logout (https://www.insanejournal.com/support/faqbrowse.bml?faqid=23).
If you have a dialup ISP, your IP address probably changes too frequently for this option to be useful.