wiki:login.bml Sucks

LiveJournal's login page, unless accessed with "?nojs=1" at the end of the URL, plays JavaScript challenge/response encryption games with the password when the form is submitted, stashing the encrypted password in a hidden field and blanking the regular password field. In at least some earlier versions of Firefox, this makes it so that when the Password Manager goes to save the login, it saves with a blank password field.

This doesn't appear to happen so much anymore, but if you are having trouble logging in with accounts saved to the Password Manager from before installing LJlogin, try using the LJlogin Preferences box to change the saved password for the account. Also keep in mind that continuing to use the LiveJournal login page without the nojs switch set may cause this problem to recur.