Display issue and freezing using Exposé "show all"

[harold3k]

Hi! i have been getting a weird display error the last several days with exposé. When i active the "show all" about 1 of every 20 times my display looks like this...

http://i94.photobucket.com/albums/l110/harold3k/error.png

and about 1 time every 1 or 2 days it freeze the entire computer and i have to restart using the on/off button