This warning is an artifact of out of date code in the Kittehcoin wallet. That being read, you should ABSOLUTELY not be using a Kittehcoin wallet that displays this error.
Simply put, it’s only a matter of time before your coins are stolen from you. You can remedy this easily by sending your coins to a Coinomi Lynx wallet. Due to how old your wallet is, it might not work and is no longer supported by the Lynx development team.