This is probably a strange question, but are there any options in CCleaner, that by selecting them, would change the appearance of files in Windows XP folders from either an "icon" or "details" format to a "tile" format? I seem to have experienced this after running CCleaner, but it may have had nothing to do with this CCleaner at all.
If you have "Window Size/Location Cache" selected in the "Advanced" section on CCleaner this is most likely the culprit.