dektop icons on windows 7 ultimate sometimes dont work

[honey33]

my desktop icons e.g internet explorer and pics and other bits and bobs ever now and again they freeze up and if i double click they wont open.yet the start button and if i have the icons on bottom tool bar they still work and open close normal.really dont understand why the desktop icons keep doing this.any help would be great thanks, also if i just go to start and click lo off and log back in then all works fine and dandy so really confused.

[honey33]

does noone know how to help with this,on further investigation it seems my desktop freezes up yet the start button botton left still seems to work ok.very odd any ideas why just the desktop keeps freezeing up on me like that and how to fix please