Creatures Caves

I keep getting an error message when I try to load the game:

CSE0001: Caught C-style structured exception at 0x00513738

EXCEPTION_ACCESS_VIOLATION
The thread attempted to read from or write to a virtual address for which it does not have the appropriate access.
Attempt was to read from address 0x0000000C

Contained in: "private: void __thiscall Map::GetNearbyFloorInformation(class Vector2D const &,class Room * *,int &

" in Map.obj
Contained in: "public: void __thiscall Map::TestNewUpFootInRoomSystem(class Vector2D const &,class Vector2D const &,class Vector2D const &,float,float,float,float,int,bool,class Vector2D &,float &,float &,bool &,int &,bool &,bool &

" in Map.obj
Contained in: "protected: void __thiscall SkeletalCreature::UpdateFeet(void)" in SkeletalCreature.obj
Contained in: "public: void __thiscall SkeletalCreature::UpdateSkeleton(void)" in SkeletalCreature.obj
Contained in: "public: void __thiscall Skelet

The only thing I've been doing differently is I downloaded an agent, the selective pole that allows only certain creatures to pass. Could this have caused me to lose this world? I know there's some agents that are unreliable that cause the game to crash. If you have any advice to help me save this world I would appreciate it.
Thanks.