Note that I have re-downloaded the game, its launcher, and have done the necessary steps to install it completely again.
When I was playing a game on Blockland Multiplayer once an error came up - Make sure Blockland in Documents is readable (I think that was it.) I couldn't understand what it meant and closed down the game. However, when I opened it up again from the launcher, it just crashed after launching. It didn't even bring up the game, just after the launching process had completed it quit. I even tried another download. Didn't work.
Has anyone else had this problem??