Minecraft 1.7 introduced a new bug on my system that causes blocks to deform if I'm near them, and looking in a certain angle.
This happens on every Minecraft that's 1.7 or above, modified or vanilla, it happens every time.
I have the latest working graphics drivers installed on my system. This means that I can't update my drivers anymore. Also, this specific version I have is the only driver that has a working OpenGL support, so I can't do anything driver-wise.
The last three images are from Minecraft 1.6.4, the others are from Minecraft 1.7. I tested this on Minecraft 1.7.10 and Minecraft 1.8, the results are the same, even on the latest 1.8.7 version.