I was playing bootstrap modal window. I have created a html file. Downloaded and linked bootstrap resources (both js and CSS). Copy pasted the html snippet from bootstrap website. But when clicking on the button to show modal window, modal window appearing for a fraction of sec and disappearing immediately . After googling and checking my code found the problem. I have included bootstrap.js at 2 places. One in head and another in footer by mistake. As per net, it seems same issue can occur if you include individual js file (bootstrap.modal.js) and bootstrap.js. So check your code and remove duplicates. That will solve the issue.
Fix : Bootstrap Modal window disappearing immediately