This may be a stupid question, but I've got to ask it... He does know how to turn caps lock off, right? If he's tried this and it still doesn't work, your description of the symptoms makes me think that there's something wrong with the caps lock key that's making the keyboard think it's being pressed. (I say that because, if you click on an item and then click on another item with the shift key pressed, the PC will select all the items between the two items clicked on - which is what seems to be happening when he clicks on shortcuts on the desktop.)
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