Apple Mail 4.5 Deleting Trash

I'm finding that Mail 4.5 is taking the initiative and deleting trashed mail older than "today". My accounts are set to delete trash "Never". I prefer to comb through it periodically and clean house; so it doesn't get filled to overflowing and, at least by my reckoning, shouldn't be wiping out either Sent or Trashed emails; yet it's doing both. I'm guessing this might be some kind of corruption, but not where to look to clean it up.

-gf