My computer goes to sleep during boot up

For some reason my MacBook 2.16 2007 Core 2 Duo (Z5W) only does this when the battery is installed. Without a battery installed it boot up and operate just as expected. Even if the battery is dead the result is still the same the backlight will shut off, the hard drive will power down, and the front LED light will begin to pulsate. This starts to happen in the beginning of the boot-up before the Apple logo appears and if the computer is awaken via the mouse or keyboard it will immediately return to the sleep mode; then the only way to regain control of the system is to reset the machine or via a Safe Boot. The Sleep/Switch was replaced with no success. Has anyone here ever experienced this or have any idea of just what is going on? Thanks in advance.