Hey RJM, are you getting that error when you have 2 instances of LF open? I've only run into that problem when I had 2 seperate threads open (via Firefox tabs). The second tab doesn't retain your 'login' if you try to post within it... I always had to make sure that my actual post was in the 1st tab (or first instance) of LF.
Though I highly agree with what Jan Gaarni
I do that now more often than not.. especially if it's a detailed post