Hello Singh Saab
The reason why this message of "Are you sure you want to Leave this page?" is the page is dirty
Its not Crm functionality which is displaying this instead you web page feature,
To turn it on: window.onbeforeunload = "Are you sure you want to leave?";
To turn it off: window.onbeforeunload = null;
If the problem is resolved, we would appreciate a post explaining the resolution and mark the post answered and close the thread.