Hmmz, my first tought was the battery as well... What exactly happens when it doesn't start up? Any messages? Are there any sounds? Does the monitor switch out of 'sleep'? Maybe the CMOS-chip itself is incorrect (did you flash it? If not - try that).
when it doesnt start ,nothing at all happens..it sits there quietly humming away..when it fianally boots the monitor comes out of sleep mode and it beeps once and loads like a normal computer should..

i dont know what you mean by"flashing" the chip...im sorry i still am relatively new.but the thing is it used to work at a point in the not so distant past so i dont know why the chip would become wrong... thanks for your very fast response as well