Postback does not work

Hi,

I have the following problem. While continuously developing my web site, at the certain point I found out that a postback stopped working on different pages of the web application. Examples are links in LoginView control (master page), radio button lists (content pages), etc. 

I can found t

he function in a page source

<script type="text/javascript">
//<![CDATA[
var theForm = document.forms['aspnetForm'];
if (!theForm) {
    theForm = document.aspnetForm;
}
function __doPostBack(eventTarget, eventArgument) {
    if (!theForm.onsubmit || (theForm.onsubmit() != false)) {
        theForm.__EVENTTARGET.value = eventTarget;
        theForm.__EVENTARGUMENT.value = eventArgument;
        theForm.submit();
    }
}
//]]>
</script>

and I can find function calls properly placed in a page source, an example (one of radios of the mentioned radio button):

<label for="ctl00_cphMiddle1_wzrdOrder_rblDeliveryType_0"><img style='margin-left: 3px;' src='http://localhost/Images/Order/GoodTeaPoint.png' alt='' onclick='this.parentElement.click();' />&nbsp;&nbsp;Osobní odběr Praha 4 - Good Tea Point&nbsp;&nbsp;(0 Kč)</label></span><br /><span style="color:#696969;font-weight:normal;"><input id="ctl00_cphMiddle1_wzrdOrder_rblDeliveryType_1" type="radio" name="ctl00$cphMiddle1$wzrdOrder$rblDeliveryType" value="58" onclick="javascript:setTimeout('__doPostBack(\'ctl00$cphMiddle1$wzrdOrder$rblDeliveryType$1\',\'\')', 0)" />

I can click the links or controls and it simply does nothing. It is the same like having AutoPostBack set to False.

Not a long ago it was working properly but it most likely started with one of changes I made to the application but I am not able to find what I did wrong. The problem is not browser dependent and the behaviour is the same on Win 7, XP and Win Server 2008.

Any suggestions? Thank you.