After a form is filled and "submit" pressed, the "submit" button reappears by itself.

Hi Everyone,

I built a form, inserted the scripts (lightbox option, though this happens regardless); the form itself works fine, but after pressing "submit", the page refreshes to the below image. I have to press the X to close the window, otherwise pressing "submit" just repeats this screen. What's going on? I want the user to continue onto the page in the background as they intended.