This post will show you how to enable or disable or change hot corners in osx lion
goto
system preferences > desktop and screensaver > screensaver
you will find a ‘hot corners’ button at the bottom
(yeah, its in a strange place, thats why im writing this post!)
once you click that button you can pick the action you want for each corner
Yes, very strange location indeed. Thanks!
to turn off this annoyance you have to select the dash – at the bottom of the menu.