Problem: CB declined to logon with error 100 on Sunday morning, however the logins supplied were the normal ones on file and were correct.
Error 100 is timeout error. It's recommended that debug logs are collected as soon as the error happens.
In this case, error happened Sunday and the logs were collected Monday, so they were overwritten because they have size limitation to avoid using too much disk space.
You can increase the size of the debug logs in registry here, to avoid this issue in the future: HKEY_LOCAL_MACHINE\SOFTWARE\ComodoGroup\Common\Settings