It seems to happen to me and my friends at the same time when we are running together so it shouldn't be something on my side and something on the server or the game. I'm not sure.
*EDIT BY ANOTHER USER*
Will not be your client because your client doesnt control where your character is, from basic experience of other hackers in DayZ im going to guess this is a new part of his new security update. What Dean is trying to do is move away from clientside actions and have everything server based. Everything on ARMA 2 was clientside, meaning you could reverse engineer it to teleport you places etc. Now, this is only a guess, but the server may be experiencing lag when this occurs and for some reason, the server does not agree where you character is, therefore ruber banding you back to your last location and disabling your keys. This would be extremely good for hackers tp'ing about the map but I think it may be triggering simply because the server client architecture isnt the smoothest in the world, and when it hasnt received where you are for a while, it might assume you're hacking and lock you in position.