This actually happened to ALL 5 rigs of mine and ALL 4 rigs of my friends that are also on bonuspool. It just kept spamming something like "invalid key" "JSON error" and i couldn't even bring up any menu options in CG. I thought CG was foolproof. Oh well, back to normal after close/reopen.

Also the first time it happened, was earlier this week and it just kept saying invalid share, rejected over and over and i had to close and reopen to get it to go to backup.