Anyone know why this happens ?

[Tork64]

See the thing I circled ? Whenever it pops up like that my wow screen turns as seen below. Why does this happen and is there a permanent fix ? Also if im watching videos and overlays are turned off the same thing happens.

http://img161.imageshack.us/img161/7012/whygy7.jpg

[AngelGraves13]

I don't know...I get the same thing for a split second when I exit a Source engine game.