I had Sony Laptop with Win 2000. I don't know what happen suddenly I can not turn off this laptop. I try many times to click "Start", click "shut down", click "shut down" in the window again, but nothing happen. While I push power buttom to turn off power, the message came out said -- " pc prepare to standby", then screen of laptop is off, but machine look like in standby condition, while I turn on power, machine back to desktop immediately. How do I can shut down laptop completely ?

You might want to run a spyware/virus scan. Seems like some process is running that your system can't kill during the shutdown process. While you're at it, you also might want to check your startup environment and see if there's anything in there that shouldn't. Clean out your temp folders... c:\windows\temp c:\documents and settings\<your account>\local settings\temp c:\documents and settings\<your account>\local settings\temporary internet files\ ...and install current patches & hotfixes.