Graphical error

2013-09-24 19:49:47 [CLIENT] [INFO] Setting user: CousAndCoke
2013-09-24 19:49:47 [CLIENT] [INFO] (Session ID is token:cf37a16196da4e429f21becd6b27c737:dec30ec743254637b6d704b28c2a142b)
2013-09-24 19:49:47 [CLIENT] [INFO] LWJGL Version: 2.9.0
2013-09-24 19:49:48 [CLIENT] [INFO] Reloading ResourceManager: Default, Darklands.zip
2013-09-24 19:49:49 [CLIENT] [SEVERE] Using missing texture, unable to load: minecraft:textures/blocks/sandstone_side.png
2013-09-24 19:54:11 [CLIENT] [INFO] Stopping!