I was on a superflat Lan world, not hosting it. The host and me where on win10.

When I used /execute @e ~ ~ ~ /execute @e ~ ~ ~ /execute MyUsernameHere ~ ~ ~ setblock ~ ~ ~ dirt, the game froze after the chat box started disappearing. It was about 1/5 gone. It took me a long time to close the game. it did not properly crash.

It took me a long time to free my pointer. Then It did not show in task manager, so I tried right clicking on the glass block logo and press close. No luck. It reappeared in a fraction of a second. I checked taskmgr AGAIN, minecraft(2) was in the background processes. I clicked end, it closed, BUT said I needed admin!

Me and my friends had this same issue with navynexus's sand player launcher while watching other players. (superflat and Lan) on ios and win10. Me(on win10, the host in this time it happened) It was always me the host on that world, the only world we had sand stacking launchers in. But this time, I could X out of use task manager(I forget which)