I have reinstalled XP Home 21 times since Dec 01. I have always used " the switch off " option for the screen after 20 minutes. Most of the reinstalls have been for freezes that could only be got around by rebooting. This time after the last reinstall and with the power option turned on it happened again. Since turning the power option off I have not had any freezes. It may just be a coinsident but worth a try. POP
to woodchip and matt1234, I do not have a problem anymore because I do not turn off the monitor. I have not turned off the hard drives so that should not be the problem, the power supply has been changed for a 400W some time ago but made no difference. I hope that it might help someone else to get too the bottom of a very baffeling fault. There was nothing on Drwatson errors or comp. management errors.
That's very interesting, I've just checked and my hard drive was set to turn off after 10 minutes, I've changed it to never. If this cures the "freezing" problem I am having with my optical mouse I will be in your debt.