Very often, I've found myself in "void" areas because of glitching through a unpassable object.
This seems to happen more often while running inside buildings.
Buildings it's happened in:
Large Elektro building opposite fire station, from 3rd floor to under stairwell.
The Military building in Chapaevsk - Teleported through the floor and landed a considerable distance from the building (and died)
Occasionally these void zones can be escaped by exiting and reentering server (thought the 5 minute login timer can cause this to be a problem - as it sometimes requires several relogs)