Reinstall.
Keep add-ons or don't keep?
Mint, he already reinstalled blockland so that is not needed. Try flushtexturecache(); ?If that doesn't work, try reinstalling graphics card drivers.
Agh, and try without addons.
Just reinstalled not keeping old add-ons, still doesn't work D:
Do you have the file base/data/shapes/brickTOP.png ?