Font problem

[squareyes]

Hi all,
I have installed a number of ttf fonts on a friends machine.
I copied them into /usr/share/fonts/truetype , and they are all 
accessible/usable
by Abiword, Gimp etc. The problem is that he has added 2 users to his 
system (Grand daughters)
these new fonts show on both, appear in the fonts lists on everything, 
but are not usable.

They show in  /usr/share/fonts/truetype on each user, but have an X 
attached to them.
Am I missing something obvious? I have "Ubuntu unleashed" book but 
cannot get any ideas from it.

Many thanks in advance for any help.
Take Care
Winton