Piston Disappears, Turns Invincible

I went down to my skeleton spawner. It uses a couple of sticky pistons to crush skeletons. But, my game crashed. It had a green line of static running down from the top left corner to the middle of the bottom of the screen. I saved, and restarted minecraft. I went back about 24 hours later, and i tried to use my spawner to get some bones. But, the blocks of cobble wouldn't move. They stayed extended. So, I went in the back, checked my redstone circuit. It was fine. I checked my pistons, and they were gone. I could walk through them, but I couldn't destroy them. I took some pictures, and tried to place a block in the space the piston occupied. The block was placed, and then it disappeared, along with the piston.

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EDIT:

The pistons are gone again. This time, no crash, and no out of date java. While I'll keep my old report, I'm now very confused.