One of two things could be happening here.
1) You are on a computer in which you do not have admin rights and someone has locked your account from accessing installed files.
2) You ARE the admin, but you're running Vista and haven't correctly set up your computer to allow this sort of thing.
At least, that's my diagnosis.
The one and only,
Those who live in the past, are destined to insanity. Those who live only for the future, will be slaves to their ambitions.
Those who live in the moment... only they, are truly happy.