I have the exact same problem, just to let you know.
I've studied the forums, and no help surfaced for those in need of help on tis topic.
Your video card is an ATI product, most likely a 9550 / X1050 or of that nature, or you have an HD card.
Either way Blockland is not able to handle such a problem and thus you would need to buy a new card JUST to play this game.
I don't recommend this action seeing as ATI cards are top of the line for handling high, graphic intensive gameplay such as Oblivion or certain Console games on your computer.
You can try flushtexturecache(); by typing it into the console but that WILL NOT help you at all. I'm posting it to keep others from acting tough and helpful with that lame fixall / endall command.