As it turns out there seem to be three common reasons people are getting this error message.
1) Anti-virus software interfering with the install. This goes double if you are running AVG anti-virus. Disable the resident shield protection and try again.
2) You are in Windows Vista, and you didn't run the patch as an administrator. Right click the patch, and run as administrator.
3) Use of the wrong version of the patch. There are different downloads for boxed versions and digitally purchased versions. Re-download the patch here:
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