Display bug of some textures and entities

yesterday , i was playing with the new and awesome observer in a flat world (with the biome "ender") ... it was cool... But today some chunks are flashing around where i build... in my setting, i try to change the set up ... it's stop flashing when i active the VBOs, but inventory start to bug.

Plus, the enderman are very weird.

My computer isn't fast, but it's strange.