trouble in pc

Sir, I have intel celeron 400 mhz,and 810 chipset motherboard oftenly I start my pc talke long time and its show me blank screen.when its start there date and time is wrong then I manualy set but when i shutdown pc again he wrong date and time when I check the BIOS there is show me in CPU SPEED MHZ: 133(66*2) what is meaning .and also show me stnd cmos setup the primary master is AUTO. its auotmaticly detected the hard disk (hard disk is 20 gb)
thanks