a box poped up and said reference (.00000000000000) could not be found at (.00000000000) click yes to termanate or cancel to debug.

I thought it was a scam or just a pop-up but it looked real enough but i still click the X at the top. did i just do something stupit or what? after I clicked that the minimize button and close button turned white and old looking at the top of my screen and now I dont have tabs anymore. whats going on?