I have experienced something like this before but couldn't reproduce the results. I could hear local zombie agro, was getting hit by it but couldn't see it.
May 10 2016
Same issue here. Has happened in the past but only did it once in each instance.
Currently trying to leave the NWAF, getting well past Grishno and it sends me back, 3 times now on two different servers.
Win7 64bit. 0.30.113860 . Ping average 25, bandwidth 450
Shooting zombies with an ACOG at 100m plus is nearly impossible. The amount of spread and drop even when rested and at prone is far from realistic. MPBR of a 55grain .223 REM is in the region of 240yds, at 100yds I should be hitting high with out noticeable sway even with a decent breeze. Presumably we are shooting mil spec rounds anyway with marginally more power.
My first character died due to either hunger or thirst. Hasn't happened since, if people pay attention to there characters needs and focus on keeping them fed and watered they shouldn't have issues. The food usage seems extreme but its certainly not unplayable, water usage is not extreme.
It would also appear that when i'm watered and fed, i don't get tired as quick, or at all.