Monitor won't shut down

Hi Guys,
I was running 98se and loaded XP Pro over it.
Now when I shut down the PC I get the "It is now safe to turn off...." but the monitor stays on - it shut down under 98se.

Am I missing a setting somewhere? I'm an absolute newbie to XP......

Thanks,
Den

 

The monitor is NOT going to shut down under any Windows ! The monitor only went black as the computer did not give it any signal.

This could happen under XP if it cannot detect ACPI system. Its not a problem as such because you can just switch off the system and everything would be fine.