how to find solution????

SOMETIMES WHEN TURNED ON MY ACER ASPIRE T180 DOESNT GET PAST THE LOGO SCREEN.OTHER TIMES WHEN USING IT PC FREEZES AND SAYS NOT RESPONDING. NOTHING WORKS, AND I HAVE TO PRESS OFF BUTTON AND HOLD UNTIL OFF. THIS SECOND PROBLEM SEEMS TO HAPPEN WHEN FIRST TURNED ON WHEN TURNED OFF AND THEN ON AGAIN IT DOESNT HAPPEN

ANDREW
June 2009