Interestingly enough, I use Firefox and have no problems with posting and uploading images, even though I do have my passwords stored. This may or may not be because I have been attempting to adapt LJLogin and have a semi-functional version installed in my Firefox. The things I haven't been able to get it to do, at this stage, are recognize which account is logged in, and auto-switch between accounts -- two things that I think are a cookie issue. If you'd like, I can send you a copy of my working files; maybe there's something in there that'd key you in on why others are having problems with saved passwords.

Actually if you have more than one password stored its not a problem. Firefox attempts to autofill the username/password fields if you only have a single username/password saved into the browser. This confuses the update.bml page and assumes you are trying to log in as a different user.

Aha! Hurrah for having multiple accounts, then. :D