The bug is caused by Office 2003 (and 2007 I suppose) Installation that overwrites the registry to use a 32bit only IconHandler for XML, HTML, MHT etc. files!
HOW TO FIX
You need this free tool (or similar to edit filetypes): Default Programs Editor
and system default tool RegEdit.
WHAT TO DO
1. Open RegEdit (from Start enter "regedit" and run the found program) and go find Computer\HKEY_CLASSES_ROOT\xmlfile
2. Modify the subkey 'DefaultIcon
' from (Default), REG_SZ="%1"
3. Delete the subkey Computer\HKEY_CLASSES_ROOT\xmlfile\shellex\IconHandler
and then close RegEdit.
4. Run 'Default Programs Editor' you've just downloaded as administrator
5. Go to 'File Type Settings', 'Icon' and search "xml" extension (if it fails 1st time, search again and it will re-build the list). You should find "Document XML" listing .rels, .xml (or just .xml). Select it and press button 'Next'.
6. Press button 'Browse...' and insert as the resource dll %SystemRoot%\System32\msxml3.dll
. Double-click on the first image in the DLL and the Browse window will auto-close.
7. Press the button 'Save Icon' in Default Programs Editor, still open, window.
You should see again the usual little-world icon for XML files! Enjoy!
It may happen the same for HTML, MHT etc. files, forced to use a 32bit IconHandler by Office 2003/2007! You have to do the same (i.e. delete IconHandler subkey) for those Computer\HKEY_CLASSES_ROOT\mhtmlfile
etc.)! Should be enough, no need for Default Program Editor. You may need to reset also IE as the Default Program
to make HTML, MHT etc. icons back.