In ASP.NET, ENTER key on a FORM with a single Input Field, will automatically SUBMIT.

This happens in IE, Chrome, but not in Firefox.

Solution: add another hidden input field. Such as:

<div style="display: none">

    <input type="text" name="hiddenText" />

</div>

Reason:

Because IE and Chrome following HTML2.0 Specification exactly.

According to HTML2.0 Specification, 8.2. Form Submission:

When there is only one single-line text input field in a form, the

   user agent should accept Enter in that field as a request to submit

   the form.

http://tools.ietf.org/html/rfc1866#section-8.2