Thanks to setek, I have found a solution, so I'll post it here in case someone else faces the same problem.
Overlay opacity doesn't work very well with the latest Chrome update (33), so we have to put opacity: 0.0X
; where X is some number, instead of opacity: 0;
I found that code in my js file and replaced
overlay.fade('in');
with
overlay.fade('in'); overlay.setOpacity(0.01) ;
Not sure if anyone has the same javascript file, but this is what helped me to solve the problem.