I did a clean install of Win 7 32bit last week and I am facing this issue once in a while. The desktop icons can't be used I can't click or select any icon, also right click of the mouse doesn't work. I can right click on the taskbar or in windows explorer but not on the desktop. Even show desktop icon doesn't work when the above happens.
There is no specific time when this happens or it doesn't happen after running a particular program so I can't figure out what is the reason for this random fault.