Hewlett-Packard has fired back at a former Autonomy executive who is attempting to block the settlement of a number of shareholder lawsuits filed over HP's disastrous acquisition of the infrastructure software vendor. HP bought Autonomy in 2011 for more than $10 billion, but later wrote off $8.8 billion of the purchase price after discovering what it called serious accounting irregularities on the part of Autonomy prior to the deal.