Numpad's Enter key is acting like the Command key instead
Since my comment fixed your issue, I'm posting it as an answer:
You had DoubleCommand installed.
Other possibilities would have been KeyRemap4Macbook or possibly any Input Manager.
Since my comment fixed your issue, I'm posting it as an answer:
You had DoubleCommand installed.
Other possibilities would have been KeyRemap4Macbook or possibly any Input Manager.