Won't properly turn on from cold boot

Hi,

My laptop Inpiron 1526 won't properly turn on when left turn off for at least 1 day. It will turn on only after several push of the on/off switch. When the laptop boot up you can use it as if the laptop has no problem. I already tried reseating the memory, hard drive and upgrading the bios. Any help from someone who may have this problem and is now resolve? Thanks.