Not sure if you figured this out or not yet. I had the same problem. I went in and created a fake transaction for the same vendor for $1, and saved it as a memorized transaction. I then exited the quickbooks file and then opened it back up to trigger the memorized transactions pop up. Then I hit enter all. I then deleted the transaction from the 'enter bills' screen, and then deleted the memorized transaction from the list itself and voila, problem was solved. I hope this helps.
