Printing firm St Ives has discovered "serious accounting errors" in its point-of-sale division. The company, which prints the internationally successful Harry Potter books, said the mistakes mean its profits for the year ended 28 July 2006 would be approximately £2.8m lower than original market expectations. In a statement, St Ives said the errors resulted from costs not being properly expensed, an over-evaluation of work in progress and unrecoverable debtors.