I did this the other day - except it a bit of the other way round.
Something was messing with my click-able links under User Accounts on XP but didn't affect the Admin accounts - links just didn't work.
EVENTUALLY found out it was Star Downloader interfering. How did i find out? Well i swore that the only change i made was installing newer mouse drivers. It wasn't until i used GoBack to go back to before the drivers where installed that i noticed a setup program in my download folder with the drivers.
I tested the links - they worked.
Installed Star Downloader (the mystery setup program) and the links stopped working... I'd forgotten all about installing it!!!