CPU running SLOW till operating system gets control

Hello,
I have an HP Pavillion dv8 1334us, 64 bit, about 4 years old. It has, several times, gotten into a state where it seems to be running at 1 tenth speed or less until the operating-system is fully loaded. (windows 7 or Ubuntu 12.04) After 5-15 minutes, it does start with the GRUB menu. What should be a beep during the start-up process often sounds like a horn. A hard reset fixed the problem two or three times, but no more. It wakes from sleep normally in either operating system, and both have no problems once they are loaded and running `````````````````````````````````