Slow CPU, Should Run At 1.66GHz Only Running At 1.00GHz?

Hi, I have a advent 7091 laptop. I have just loaded everest ultimate on it and it is telling me that the CPU is running at 1.00GHz not 1.66 which is what it should run at. Any tips or hints, and how can I get it back to 1.66GHz? 10 points For a best answer.