i have ubuntu 12.04 installed on my laptop. There is the following starting/shutting down problem:

When clicking the power button, the laptop starts for 1 second and after that abruptly shuts down. When starting again everything works normal. But after shutting down and starting again, the PC again has the same problem.

This problem wasnt there when using Windows. What can I do?

Thank you very much!

Greetings, Richter