block on html graphics

while trying to play several free online casino games I recently started having a problem in which when i click on the game i wish to play instead of the game comming up i get an outline of the game that is all black.  In the top left hand corner there are three tiny shapes square,circle, triangle that will not go away and the game will not appear.  Is this some kind of block? Anyone know how I can fix this?  please help!!!