Creative Cloud no longer recognizing valid subscription

All of a sudden, this afternoon, all my Creative Cloud apps began going to a "Enter Serial Number" screen when clicking the "Sign In" button. The valid serial number, when entered, gives a message that it isn't valid. Logging into the Adobe website and checking shows a valid Creative Cloud subscription with the same serial number. What gives? At least they are running in trial mode, but this gives me serious concern. These are mission critical apps and if they ever fail for any reason I'm up the creek without a paddle. Does someone know how to fix this?