Black square covering top left quarter of screen in shockwave games

[AlRubyx]

In several of the shockwave games, a black square covers the top left quarter of the screen. This ranges from very annoying, to completely bricking the game. I've noticed it on castle battles, hannah and the pirate caves, and gourmet club bowls, the last two of which are avatar games.

[juvian]

Never heard of that, can you show a screenshot