re-starts

My system re-starts everytime switch it on. It even re-starts a couple of times even when I give the restart from the OS. First of all it takes a while for it to power on. Then before RAm/HDD gets detected it restarts. Again it restarts during and after POST. While the OS gets loaded it...

I am having new pc with intel mother board 945 17 crt monitor 256 mb ram dual core processor since few days when I run my pc it re-starts just after few minutes. and before restarting it shows error message called...."Disattivazion monitor" and after showing this it immediate re-starts...