On Win 7, my pc clock keeps going out of synch by an hour or two a day.
When I go to double-check and correct it, after I right click on it and choose 'adjust date and time', the first thing I get is a pop-up that says, "CryptoPrevent - A restricted .CPL program has been blocked:
Allow program to run?"
Then I click on 'yes', choose Internet Time tab, and Change Settings, Update Now, and OK, and it is corrected... ...until the next day when it happens all over again.
edit: I think I just answered my own question.
I have CryptoPrevent, created by FoolishIT, which is an anti-CryptoLocker ransomware blocker.
I may have chosen unduly strict protection options, blocking my own Desktop clock. :P