Hi can anyone shed any light?

My brother has windows XP pro, and recently after a period of use, when
you go to switch off, click the "start" button the egg timer comes up
(can move around) but the computer freezes for exactly 2 mins, then when
the menu comes up, and you select "turn off computer" it freezes for 2
mins again ( with egg timer), once past this and you select "turn off"
or "restart" it turns off normally!

Any ideas folks?
--
Paul Robinson