Recycle Bin icon keeps changing
My son's computer is running Vista.
The recycle bin full icon keeps reverting back to the same icon that's used for recycle bin empty (in other words, the recycle bin icon on the desktop always shows as empty, even when there are files in the recycle bin). The bin can be emptied normally, or opened to see what files are inside, but the desktop icon always shows an empty bin.
I have gone to desktop/personalize/change desktop icons and tried to change the full icon back to what it should be, or to return the icon to its default, but it either doesn't change, or it changes for only a short time and then reverts back to showing and empty recycle bin.
Any idea why this is happening, and how I can fix it?