Thank you both for your advice. Strangely I have been using Symantec for years without a problem and Windows 98 is pretty stable but I'll certainly look into Zone Alarm. And no it is not only Vue that is affected. Once Vue has seized up there is a domino effect and Poser, OE, IE and even NIS itself may seize up and I have to re-boot. It sounds as if a .dll used by other programmes has been changed. I've had a similar experience with a Windows update in the past.