In a "flash audit," issued Wednesday, the inspector general for the Office of Personnel Management raised "serious concerns" about a proposed $91 million computer overhaul, saying it had not followed management guidelines and granted a no-bid contract with a single vendor. Office director Katherine Archuleta_a former school teacher who worked on President Barack Obama's 2012 re-election campaign— told Congress this week that her agency's computer systems were so old they needed an immediate modernization. The antiquated computer architecture, she asserted, was one reason hackers were able to infiltrate the system and make off with sensitive data on millions of federal workers and security clearance holders. Many critical agency applications run on OPM's aging mainframe computers, he wrote, including those that process payments for federal retirees, reimburse health insurance companies for claims and manage background investigations.