I am trying to make a 3D Engine using OpenGL, I've got all the model loading, 3D nodes, all that stuff done, but I get linker errors when I try to compile, it.. these are the errors:

------ Build started: Project: TheAlienEngine, Configuration: Debug Win32 ------
Compiling...
main.cpp
core.cpp
ae_3d.cpp
Generating Code...
c:\documents and settings\tom\my documents\visual studio 2008\projects\thealienengine\thealienengine\ae_3d.cpp(33) : warning C4700: uninitialized local variable 'model' used
c:\documents and settings\tom\my documents\visual studio 2008\projects\thealienengine\thealienengine\ae_3d.cpp(49) : warning C4700: uninitialized local variable 'node' used
Linking...
core.obj : error LNK2005: "struct options_t somecrazyoptions" (?somecrazyoptions@@3Uoptions_t@@A) already defined in main.obj
core.obj : error LNK2005: "struct node_t * _nodes" (?_nodes@@3PAUnode_t@@A) already defined in main.obj
ae_3d.obj : error LNK2005: "struct node_t * _nodes" (?_nodes@@3PAUnode_t@@A) already defined in main.obj
C:\Documents and Settings\tom\My Documents\Visual Studio 2008\Projects\TheAlienEngine\Debug\TheAlienEngine.exe : fatal error LNK1169: one or more multiply defined symbols found
Build log was saved at "file://c:\Documents and Settings\tom\My Documents\Visual Studio 2008\Projects\TheAlienEngine\TheAlienEngine\Debug\BuildLog.htm"
TheAlienEngine - 4 error(s), 2 warning(s)
========== Build: 0 succeeded, 1 failed, 0 up-to-date, 0 skipped ==========

I have used include guards in all the header files and I have looked through the pre-processed file and I still couldn't find where those things are defined twice.. I've attached the code in a .zip file if you want to see.