It's kinda creepy now... First, an invisible fire block that nearly burned down a jungle, even though I couldn't put it out. Now, a strip of wooden planks spanning across several chunks... It's really starting to freak me out. What is it?
41 Answer
Most likely, you are using a different texture pack that: a) Is higher than 16x16 b) Modified
If you are using a higher resolution texture pack without patching Minecraft, blocks can sometimes be invisible, texture may be messed up, and other various things, such as what you mentioned above, occur.
