Due to an error in the SP3 update.inf file, poledit.exe was not updated by the Service Pack install. To correct this problem, expand the Service Pack manually by typing:
Edit update.inf and move the poledit.exe line from the \[MustReplace.System32.files\] section to the \[SystemRoot.files\] section.
Then copy the poledit.exe from the expanded Service Pack to %SystemRoot%.
If you have to re-apply the Service Pack in the future, Expand it and use your updated update.inf file.