Shutdown = Restart

This is mainly for Zhenya/WW
So whenever my mom tries to pick the shut down computer option from windows XP pro ( All hotfixes + SP 1) the computer just restarts and she has to do a hard shutdown in order to shut it down. Not sure what is causing this. I was thinking the powersupply isnt losing power or the mobo is retaining too much power and instead of turning it all off it just cycles the power. Well any help would be nice.