Guyver1 gives the best cause/solution to this. I haven't seen this issue occur beyond the Second Mouse Button / Space Bar / Double Shift toggling. If are stuck in walk mode, it is a combination, or one of these.

Please verify and Edit as necessary.

Welp, I will verify ^ that tonight. Quite possibly could have been the issue. Makes sense given location of doors on floors above/below.

Edit: This seems to be the case, after verifying.

Confirmed via duplicate bug report.

Up-voted, but you should probably separate different bugs, and possibly obvious/verifiable occurrences. Not all zombies stand still. Can opener mechanic is possibly intended as there probably aren't checks currently to interact with other items in your inventory through right click.

Backpack thing is pretty fubar though, good catch.

Possibly same issue, please verify and edit. ^^

http://feedback.dayzgame.com/view.php?id=553