I've downloaded it for the second time. The first one I was clicking on the menu like and nothing happened... so I deleted the files, sorry
But this time I tried my keyboard and I runs better.
You should hide mouse pointer to avoid this error.
Concerning your game, I did have fun with it ! But in a ball game, ball movement should be the most important, so like already said by someone (somewhere), 45° angle are to be improved.
Quote: "but it had nothing to do with anything that either of you said"
I think you should listen to Spooky & Blanky without a doubt
Another example : why the hell do you need a 512^2 blue.png map !? that's a tilled pattern, you could have 100% the same in a 256^2 file 4 times lighter.
Just a more-designed Pong, but a nice game for a first attempt anyway !
Keep on