Try the Repair Icons option in TweakUI: (147 KB file)
http://www.microsoft.com/windowsxp/downloads/powertoys/xppowertoys.mspx
XP's Tweak UI tool gives users more options
The Repair branch
The options found on the Repair branch are handy troubleshooting tools that can allow you to easily fix a number of common problems (see Figure D). Click the drop-down list to see a list of actions that the Repair tool can perform. After you select an item from the list, you just click the Repair Now button to restore that item.
The first item on the list is Repair Icons. To improve performance when loading icons into the user interface, Windows XP keeps track of all the icons currently in use in a special cache file. If this file becomes corrupted, the icons used in the user interface will become scrambled. For example, you or your users may discover that your icons are all black or have mysteriously changed. You can quickly set things straight by choosing Rebuild Icons.
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TweakUI for Windows XP - Tips
http://windowsxp.mvps.org/twktips.htm
Features in Tweak UI. This is based on version 2.10.0.0 for Windows XP
(SP1 and higher) and Windows Server 2003.
http://www.winxpsolution.com/Tweakuixppro.aspx
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ShellIconFix - Utility to repair the shell object icons in Windows XP
http://windowsxp.mvps.org/shelliconfix.htm