It's two diffrent things that's happening, but one of the bugs have been reported a lot, but i will mention it anyway.

1) Chunks are re-generation.

I have no idea why.. I had the bug a year ago on another world, so i created a new world. I have only been playing on released version, so no snapshots.

2) Chunks are not showing.

I thinks this is just a visual glitch, cause if you're updating the blocks, it's creating the outline of a invisible block, but if you're triyng to break that block it shows what type of block the game thinks is there (I tested it on top of the nether, so there was bedrock) But this should be easy fixable

I will add some screenshots and a world download, if that will help.
http://www.mediafire.com/download/2h68ccoo5342wr4/Minecraft_Bug.rar