|Sounds like your iconcache file needs rebuilding.|
Empty the Recycle bin. Next delete all the desktop "shortcut" icons (ones with an arrow only) into the bin. Leave all system icons, such as the Recycle bin itself, on the desktop. Reboot the the machine then restore the icons from the bin. I've found this process sometimes jiggers the iconcache file into rebuilding.
If you are fussy about where your icons are placed on the screen then take a note of that first.
How to know you are getting old 3:
You start converting your age to hexadecimal