MAJOR rendering bug!!!

many places in my world have strange colors, they can be green,orange,brown and many others. Some of them are flashing rapidly, showing the original and glitched color. Some just stay glitched, but some can changed back to normal texture after placing a block on it,  it only affect the side of blocks. My friends also experience the same problem. I don't think it is a texture pack glitch since it also happen with a world without any texture packs.