After refreshing browser, Failed to load the bootstrap javascript: ./VAADIN

Hi everyone
I know this problem is very familiar but this one is little bit different.
In my project, i use vaadin 7.3.8 on jetty 8. Project source, theme and widgetset compile processes are perfectly done. After compile all this stuff, i can reach my application’s ui. Every thing is perfect until i refresh browser. After first refresh, this problem shows up , Failed to load the bootstrap javascript: ./VAADIN/vaadinBootstrap.js. Then i refresh browser again , my application’s ui is loaded without any error. On third refresh , this problem shows up again. And it is going in this order. My application’s ui gives me this error between two refresh.

What should i do to get rid of this problem