Well, the google toolbar does automatically update itself and it seems the checksum algorithm did, in fact, change at least once before (and, with typical google humor, you'd still get results when you used the old codes, they just weren't the correct results
).
There was a program once (about two years ago) that calculated the checksum. It was named "PRMaster" but I doubt you'll find a copy of it unless you went around to some warez sites and trusted what you found there. Good luck with that!
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