Branches.inf

Has anyone encountered this problem while running an update manually?

XP Pro SP2... the latest updates are failing. Tried downloading one, and
installing it manually. It works fine until it tries to copy a file called
branches.inf and then it fails. A dialog box pops up to look for the file
under a different location, but the file is right there, plain as day. It
just won't copy it, so I have to cancel. When I cancel, a message box pops
up that says the installation failed. And then another one pops up that says
Access Denied.

I've tried moving the branches.inf to another directory, but it still won't
copy it. I've created another administrative user, and tried installing
under that user. I've tried some of the other various suggested fixes (too
many to remember right now) but I'm not getting anywhere. And what makes it
even worse, more updates came out recently and they are still not
installing. So it looks like they will continue to build up until I get this
resolved.

If anyone has the THE DEFINITIVE fix to this problem, I sure would like to
get a clue.

Thanks in advance for any replies,
Rick Kalifa.