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.
Own a Predator Laptop? Then I bet you have learned a thing or two from beststevie. He has been helping out in this forum for quite a while and it's about time we recognized him for it. Thanks beststevie!