Laptop not switch off or onn.. need plug / unplug

Hello,
maybe it is new PNP laptop ??

I am really upset ! I can't find any clue about my problem :
I cannot shutdown and power off my OMNIBOOK 6000 ! from soft Windows XP shutdown command or even hard switch action, the notabook stops quite correctly, and power off, and start again after 1 second or even less.... What is possible to do for this !!
Need to say also : I installed Windows XP, all was working very very fine ! Only problem was this sleeping mode that isn’t coming back correctly about screen (staying black at wake up) . But about shutdown, all was working.. for now, only way to switch on is to put AC/ plug inside, and it starts directly… and switch off by removing it at the best moment possible when hearing the fans stopping… (before it starts again)
this problem appeared without any reason (no installation, no special actions…)
I formatted and reinstalled ALL, and is the same problem staying anyway L
Do anyone think it can be from the harware itself ? (power switch) ??

So many people seems to have. Did Hewlett Packard not do anything for this ?? I'll pay anyone having the answer for me !!!

my email : [email protected]