I have been using Avast antivirus free on my Dell laptop running Windows XP Pro Service Pack 3 ever since I've had the machine. I'm had no real problems until the last program update. Starting right after the update, the machine can become completely unresponsive when coming out of hibernate. Rebooting the machine brings everything back to good working order. I've also noticed that the SafeZone browser will not open on the machine. In and of itself, this is not a big issue for me as I do not plan to use it but, might it be a clue? Is there a known incompatibility of the latest update with Windows XP?