IE10 find first button on page and trigger click event on input submit

sorry about title, i know its messy but i dont know how can i describe this situation.

we have an input field. but no form element. here is the code

<input name="search" id="search" onkeypress="SearchBox(this.value);" type="text" value="Search"/>
<input name="searchbutton" align="left" class="okbutton" id="searchbutton" onclick="SearchBox(search.value);" type="button"/>

SearchBox function checking keycode and if it is 13 (enter button charcode) sending search request. this code works in IE8/9 but in IE10 have interesting behaviour.

above code middle of the page. and we have a button element top of the page for LOGIN.

in IE10;

i enter a word in input and press enter:

• SearchBox function work,
• but behave like LOGIN button is clicked also and its a problem

note:sorry about language, english is not my native language. note 2: SearchBox() function removed. check the jsfiddle link for the latest code.