Some, but not all, of my desktop icons change designs all by themselves. This seems to happen to the more recently added shortcuts (to the desktop) and almost always after my grandchildren have used the computer to visit their game sites.
These shortcut icons still open to the correct sites, so it seems not to be a hijack attempt, and the icons do return to their original design from time to time.
I am running XP Home.

Harvey

Cibaprinter

I have experienced a similar problem but it does not relate to my grandchildren. The icons change and then a few days later they reappear.

HVAC888

Try a program like Microsoft's TweakUI, which lets you "rebuild" the icons. The icon images are usually stored in the program's .dll or .exe file and needs to be re-associated.

BenReilly

Go in your Profile folder and make show you have turned on show hidden files and folders and search for IconCache.db (make a backup just in case) and delete it. It should be automaticly recreated after your restart your computer and all default icons should be restored.

HVAC888

Good tip Ben, didn't think of that.

Another way to "rebuild" is to change the desktop color quality (i.e. from 32 bit to 16 bit).

Here is some useful info on the Icon cache Ben was referring to.