If it is a windows xp computer, you can use a microsoft tool called "Tweak UI". Download it from http://www.microsoft.com/windowsxp/downloads/powertoys/xppowertoys.mspx (the link is in the rightmost column of that page). Download, install and run it, click on "Repair", select "Rebuild Icons" and finally click "Repair now" button. I hope it solves your problem.