Trouble while Turn off

S

hi I am sai from vizag .what really troubling me was when i complete my stuff in my desktop/PC and try to turn off it restarts .The ways i tried to shut down and got the same result are:
1.alt+F4-shut down
2.start-shutdowm
3.alt+ctrl+del-shutdown
these ways never worked out for me and again my system restarts.After so much of disguss i loaded XP SP3 over my SP2, then again the same result.
Hope you geeks will undrstnd my problem and give me an appropriate way to shut down.

Here are my system cofig:
Ram:1 gb
processor: Pentium 4
no graphics card
80 gb hard disk
OS:windows XP sp3
manfacturer:Zenith

Try a system restore to a date before this issue started.

You can also press hold the power button and see if it is restarting again.

Try shutting down from task manager.

Make sure your power button (on Cabinet) is not stuck. Since you reinstalled the OS, doesn't seem like a software issue.