at a guess, one of the following applies:
• you have postings in your retained earnings account (sometimes consultants balance your opening AR load against these accounts, so if you have a void or credit on opening items, they end up in RE)
• one of your retained earnings accounts is set up with the wrong translation method (current, when they should be historical or in some rare cases average)
• your calendar is set up incorrectly, but I really doubt that