theForm.Submit error in asp.net 4.0

[obazard]

when I updated application to 4.0 framework from 3.5 framework strange error started appearing and it only appears when we change data in page and post back to another page it ask for stay on current page or navigate away..when navigate it gives no error and when we stay on current page it gives error in the code mentioned below :\[code\]function __doPostBack(eventTarget, eventArgument) {if (!theForm.onsubmit || (theForm.onsubmit() != false)) {theForm.__EVENTTARGET.value = http://stackoverflow.com/questions/15804348/eventTarget;theForm.__EVENTARGUMENT.value = eventArgument;theForm.submit(); <-----error in this line}}\[/code\]i don't have any Ajax control on that page.thank you