toshiba satellite 300 series on/off problem

I turn on my laptop, it boots completely up to icon screen last 20 seconds on then laptop turns off, what can it be ?

You may have an application or service running at startup that is causing this issue. Try troubleshooting by running a clean startup (aka clean boot.)

Troubleshoot Application Conflicts by Performing a Clean Startup

ok, I didnt want to open a new topic so I used this one.
I plug in my laptop to charge battery and the laptop works fine
in battery mode not plugged in but if I turn on the laptop while plugged
with battery on it turns off or if I take out battery and turn on laptop
while plugged in it turns off, last like 12 secs on..
I tried using another charger from same type laptop (toshiba 300 series)
and it still turns off but like I said b4 in battery mode no plug at all it turns on fine.