MULTIPLE WINDOWS OPENING ON WINDOWS XP

MY PROBLEM IS THAT WHEN AM USING WINDOWS XP,MULTIPLE WINDOWS CROP UP AND STARTS MOSTLY WITH THE START MENU,THEN OTHER WINDOWS LIKE DISPLAY SETTINGS etc.I HAVE TRIED ANTI-VIRUSES BUT DON’T SEEM TO WORK,FORMATTED THE HARD-DISK TO NO AVAIL AND EVEN CHANGED THE HARD-DISK BUT THE SAME PROBLEM OCCURS.
I NOW THINK IT MIGHT BE A HARDWARE PROBLEM AS WHEN THE WINDOWS ARE OPENING,THE MOUSE CURSOR ALSO MOVES ON IT’S OWN.NEED SUGGESTIONS ON THE NEXT STEP I SHOULD TAKE URGENTLY.