DARKRP i have an error i dont know how to solve

CBaseEntityList::AddNonNetworkableEntity: no free slots!

[ERROR] lua/autorun/client/holster.lua:808: Tried to use a NULL entity!
1. SetNoDraw - [C]:-1
2. fn - lua/autorun/client/holster.lua:808
3. unknown - lua/ulib/shared/hook.lua:109


in my serverthis is what reads in my console, and it lags yourself in the server. cant use even f4.

But it wont lag anyother players, it just happens randomly on some players at sometime, can anyone help?