cannot change material

Whenever I try to change the material on a part I get thefollowing error message:-
"Access toC:\\programfiles\\solidworks\\lang\\english\\colorswatches\\dull.sldclrwas denied."
I was told it was because the file/folder was read only, I changedit from read only but it just changed back.
Any ideas? I am taking the cswa exam shortly so it is essentialthat I can change the material.
Thanks in anticipation Derek Westwood.SolidworksAdministration