Mostly the crashes happen randomly without any clear reason. Usually dozens of players crash simultaneously. The crashes happen only on zombie maps.
The crash message:
player/custom_payer/legacy/tm_phoenix.mdl (2) at nan nan nan on contact with player/custom_player/legacy/tm_phoenix.mdl (2) at nan nan nan, crash. dist = -1, minq = 100000002004087734272.000000
The model can be any that is set to players - either a standard one or a custom. But it is always the same in the first and second parts of the message.
On one specific map it happens almost every round:
At the end of the map there is an island and if somebody throws a grenade into the stacked boxes and there are more then 1 player the crash happens.
Crash dumps are not generated. I checked all the plugins and extensions and it looks like something wrong inside the engine and not sure if zombie reloaded has something to do here. The player positions on server side within the gameframes when the crashes happen are neither zero nor nan.