In a bit of a hurry (have to leave in a few) but I gave it a few runs and found a new bug:
The problem is now somewhat reversed, in a way. Whenever pacman enters the right side of the screen, he leaves a mark there (similar to the marks before) except now it stays there the entire game session. The ghosts are able to leave marks on the right side of the screen by both entering and exiting either side. Pacman can only effect the right side of the screen by entering it. I'm able to clear the marks by going into window mode, then back into fullscreen (or vice versa).
I'm not sure if this has anything to do with it, but the right edge of the board is cut off by a few pixels.