pressing Enter on Dropdownlist causing postback

User select the dropdownlist and key in something then press enter caused the screen become blank.

everything the press enter the screen will be blank.

http://stackoverflow.com/questions/19494198/pressing-enter-on-dropdownlist-causing-postback

add code below will solve the issue
UseSubmitBehavior="False"

ex.
<td align="right"><asp:Button ID="btnSave" runat="server" UseSubmitBehavior="False" Text="Save" /></td>