Blocks I place are randomly changing into other blocks.

I have recently came across a bug where I place a block down like Grey concrete, on the ground and suddenly it changes to grass, sandstone or any other blocks I previously used. Further more when Im done working on my world is load it up again and there is random block all over the place.

Note the wall I was building should not and did not look like this.

No mods

Texture pack
City texture pack
Sspe shaders.