When down-changing the Option | Updates and Statistics “Update frequency” from “Service Release Candidate” to “Service Release” Rhino fails to clear the C:\Users\[USER]\AppData\Local\McNeel\McNeelUpdate\DownloadCache\ folder. This results in the user continuing to be presented with an update that the user does not want.
I know: there are only three people on the planet who might care… 
(Yes, “down-changing” is a term I just made up.)