Anyone telling you to delete cache.db knows that you're going to have to do it over and over.
Mac Snow Leopard will get that error if you connect to a server, leave, and connect to another. You're gonna have to restart your computer each time you want to go to another server. You have the choice.
Every time you enter a server, cache.db is remade. So either way, you're gonna have to re-open Blockland.
Why must Macintosh be so simple that it can't run many things smoothly, yet be so complicated that it takes thousands of dollars to upgrade?