Denied access to files by XP Pro SP2

G'day Team,

Am having much trouble when I try to open some programs, not all. I get the
following message.

"Windows cannot access the device, path, or file. You may not have the
appropriate permissions to access the item."

I can't start my firewall for instance. I need help as I'm clueless about
the permissions and ownership things. Maybe I've been hacked? Maybe not.

Any help appreciated.
Regards,
Greg

Incidentally, I'm the sole user and administrator of this PC.


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