My computer is not turning off

Hi!

I have a PC with an ECS L7VTA2 Motherboard, AMD Althon XP 2200+ Processor and Windows XP Professional SP3 installed on it.
Sometimes, but not always, when I try turn off my computer, it appears the typical blue screen saying "Logging off...", "Saving your personal setting...", and finally "Windows is shutting down...". When is the moment for the computer to turn off, I can hear a sound as it would try to turn off, but it doesn't (the cooler is still functioning and the power led is on). Then, If I press the Reset button, the system will turn off immediately.
I have encountered this odd behavior for years (but sometimes the PC is turning off without any problem) and since then I reinstalled Windows a dozen times.
I'd be glad if you helped me to figure out what's wrong with my computer.

Thanks!

I means Display gone out but fans working is n't ? That because power management failure of OS, Check power management stuff in control panel. and re-install motherboard drivers again

Hi,
Thanks for your reply.
The monitor is displaying "Windows is shutting down..." and the fans are working.