This Problem does occur without alt tabbing.
To be more specific, I normally tab out a few times during my game sessions but the bug even occurs hours or many minutes later.

My character also reseted after Dayz crashed (not every time but twice).

I have the same Problem, my DayZ crashed every 30 minutes. And finally when i was driving my DayZ crashed and my character did reset.

It's just the typicall windows error window which pops up, DayZ stopped working. Options: Search for a solution online or close the Programm.