I have an Intel 865PERL motherboard with Intel P4 3Ghz HT CPU on it. Using Windows XP Pro with all updates installed. Recently I started experiencing this weird problem where my system would completely lock-up to a hilt with no return (mouse cursor dies, CTRL+ALT+DEL or ALT+TAB doesn't work) and I'd have to turn off and turn system back on or reboot thru the switch to get it running again. Also sometimes when I leave computer overnight, I wake up to find that it has shutdown on it's own (with no electric outage). I try turning it back on using the power button and it doesn't work. So I pull the electric plug off for a few seconds then plug it back on and power button works again and system starts as usual. What could be the cause of these two problems (which I think might be related to each other) ? I'd appreciate if someone can help me diagnose the cause of this problem.