Can't open file

Hi,
I've been working on my Random Mission Pack and have come across a frusturating problem, whenever I attempt to randomly generate a mission 22 x 22 pieces somewhere near the middle it begins being unable to open the mission file to write more data. I've traced this problem to a failing of

stream.open (fileName, (FileStream::AccessMode) accessMode)

in

bool ResManager::openFileForWrite (FileStream & stream, const char *fileName, U32 accessMode)
{
   if (!isValidWriteFileName (fileName))
   {
	  Con::warnf("Filename '%s' is not valid.", fileName);
      return false;
   }

   // tag it on to the first directory
   char path[1024];
   dStrcpy (path, fileName);
   char *file = dStrrchr (path, '/');
   if (!file)
   {
      Con::warnf("Filename '%s' cannot be saved in root.", fileName);
      return false;      // don't allow storing files in root
   }
   *file++ = 0;

   if (!Platform::createPath (fileName))   // create directory tree
   {
      Con::warnf("Could not create a path for filename '%s'.", fileName);
      return false;
   }
   if (!stream.open (fileName, (FileStream::AccessMode) accessMode))
   {
      Con::warnf("Could not open a stream for filename '%s'.", fileName);
      return false;
   }

   // create a resource for the file.
   ResourceObject *ro = createResource (StringTable->insert (path), StringTable->insert (file));
   ro->flags = ResourceObject::File;
   ro->fileOffset = 0;
   ro->fileSize = 0;
   ro->compressedFileSize = 0;
   return true;
}

When I try to run the debug version XCode (yes, I'm on a mac) displays these pics.
http://img242.imageshack.us/img242/7136/picture1th0.png
http://img169.imageshack.us/img169/9471/picture2ko1.png
It also says

Quote: Program received signal: "EXC_BAD_ACCESS"

Can anyone help me? If you do I'll send you a free coy of my Random Mission Pack.