I would consider that a temporary workaround, but not a solution. With "Maintain connections" unchecked, CF is now creating a new connection with each query. You can imagine the performance degradation on high-traffic sites that will result. The fact that the error manifests after a lull in activity, and that unchecking "Maintain connections" fixes it, would point to a bug in CF's connection pool handling for MySQL.
Europe, Middle East and Africa