See attached pic. The blue triangle appears when I push the cursor into the corner. The only hot corners I have active are the bottom two. The top right corner (the other inactive hot corner) doesn't do this. I rebooted earlier just to see if it would go away because I've never noticed it before and thought it must be new. When I started up again it was gone but now it has come back. It is actually getting in the way of quickly running Software Update because I can't just throw the cursor over there and click to bring the menu up. When I click the blue area nothing happens. What the heck is it?