I've seen this many times on our little AOD270. Occasionally something just won't startup correctly, and comes up with the "xyz has stopped working" message. To be honest, e-power tray doesn't seem that important. I'm sure you could find it's .exe in the C:\program files\acer\acer power management\ or similar folder.
Our friend and comrade IronFly has reached his 10,000th post to our little Community. During the last 4 years he has helped countless Acer customers providing help, advice and answers. The Acer Community team feels honored to count you as our friend. Thanks IronFly!