I have found descriptions of some fixes for this that involve reducing the graphic accelerator:
http://victorcaballero.blogspot.com/...disappear.html
and
here
http://nz.answers.yahoo.com/question...8142605AASmAKu
See also
http://www.intel.com/support/graphic.../CS-020748.htm
I'll be trying that on one of my computers later this week, as I have the same problem.