Desktop issue

I am having an issue with my desktop shortcuts. After opening an internet explorer window my desktop looks OK for a while, but after a short time, all of the pictures of the shortcuts go blank.  When that happens, clicking on them does nothing and the cursor has the hourglass attached to it.

 

The second I click on the restart button, the pictures re-appear and when the computer is back online, everything works fine for a while until I open something on the screen again.

 

I have run all my Norton processes and nothing is found !

 

Any ideas?