[I'm not entirely clear what causes this and when, and yes, i should be writing outside the browser-- but without this problem, Firefox is rock solid about not losing information.]
When clicking a link and then going back, or pressing a the back button and then the forward button, the text in BUEditor-enabled textfields is getting blanked out.
I think this is site-specific because it hasn't bugged me before, and i see no other reports, but for the moment BUEditor is disabled from this (Drupal 6) site.