[G4] all a's

[Ed T]

Hi all, I'm having a strange problem with my mother in laws computer.  
She started it up yesterday to find all
menu items and file names were now the letter A inside a square in  
other words the word file was now AAAA
the word edit is now AAAA every letter is now A inside a square. Does  
anyone have any idea what is going on
with this behavior?  All programs operate normally in safari all pages  
read as always same in mail etc.
I is confused... any help would be greatly appreciated. TIA
Ed T