I have a form that would be submitted when i pressed enter in a text input field. It would skip over all my validation that i was doing in the input's onKeyDown callback function. I removed the onKeyDown event handler, and still the form would be submitted on enter. The input was not a submit type input so the submission was not expected.
This problem stemmed from the fact that the input box in question was the only text type input box on the form. The HTML4 spec states that if you have one input box of type text, pressing enter in this input box will submit the form!
I solved this by adding another input of type text with style="display:none" and a name:
<input type="text" style="display:none" name="dummyinput" value="" id="dummyinput" >
The reason for this hack being that I had bound on-enter handlers to the first inputfield of my own, and trying to prevent those would break my code also.