MIB_IFTABLE  *m_IfTable;
...
NetworkAdapter::NetworkAdapter()
{
	m_IfTable=NULL;
	Z_InitClass();
}

bool NetworkAdapter::Z_InitClass()
{
	DWORD size=0;
	GetIfTable(m_IfTable,&size,true);
	return false;
}

auch nachdem ich testweise einfach mal das versucht habe :

MIB_IFTABLE  *m_IfTable;
...
NetworkAdapter::NetworkAdapter()
{
	m_IfTable=NULL;
	Z_InitClass();
}

bool NetworkAdapter::Z_InitClass()
{
	DWORD size=0;
	MIB_IFTABLE  IfTable;
	GetIfTable(&IfTable,&size,true);
	return false;
}

gleiche fehler, auch wenn ich size=sizeof(MIB_IFTABLE) mache.
aber immer nur wenn er es das zweite mal aufruft und nur unter winxp als service, als normale anwendung gehts auch ohne probs unter xp.
also ich weiss net weiter, ka worans liegt

aba fuer alle die interesse haben ma die adapter klasse :

#include <IPHlpApi.h>
#pragma comment(lib,"Iphlpapi.lib")

#include <mbstring.h>

class NetworkAdapter{
public:
	NetworkAdapter();
	~NetworkAdapter();
	int GetAdapterCount();
	char* GetAdapterName(int index);
	char* GetAdapterDescription(int index);
	DWORD GetAdapterID(int index);
	bool EnableAdapter(int index,bool enable);
	bool EnableAdapter(char *name,bool enable);
	bool EnableAdapterID(DWORD ID,bool enable);
	bool EnableAdapterDescription(char *descr,bool enable);
	bool Z_InitClass();
private:
	#pragma pack( 1 )
	MIB_IFTABLE  *m_IfTable;
	int m_index;
	struct _adapter{
		char *name;
		char *descr;
		DWORD ID;
		MIB_IFROW *IfRow;
	};
	_adapter *m_adapter;
};

NetworkAdapter::NetworkAdapter()
{
	m_IfTable=NULL;
	m_index=0;
	m_adapter=NULL;
	if(!Z_InitClass() ) m_index=0;
}

NetworkAdapter::~NetworkAdapter()
{
	if(m_IfTable!=NULL) delete [] m_IfTable;
	if(m_adapter!=NULL)
	{
		for (int i=0;i<m_index;i++)
		{
			if(m_adapter[i].name!=NULL) delete [] m_adapter[i].name;
			if(m_adapter[i].descr!=NULL) delete [] m_adapter[i].descr;
		}
		delete [] m_adapter;
	}

}
bool NetworkAdapter::Z_InitClass()
{
	DWORD size=0;
	GetIfTable(m_IfTable,&size,true);

	char tmp[2];
	m_IfTable=(MIB_IFTABLE*) new BYTE [size];
	if(m_IfTable==NULL) return false;
	memset(m_IfTable,0,size);
	if (NO_ERROR!=GetIfTable(m_IfTable,&size,true) ) return false;
	m_index=m_IfTable->dwNumEntries;
	if(m_index==0) return false;
	m_adapter=new _adapter [m_index];
	if(m_adapter==NULL) return false;

	for (int i=0;i<m_index;i++)
	{
		m_adapter[i].name=new char [MAX_INTERFACE_NAME_LEN+1];
		if(m_adapter[i].name==NULL) return false;
		m_adapter[i].descr=new char [MAXLEN_IFDESCR+1];
		if(m_adapter[i].descr==NULL) return false;
		m_adapter[i].IfRow= &m_IfTable->table[i];
		wcstombs(m_adapter[i].name,m_adapter[i].IfRow->wszName,MAX_INTERFACE_NAME_LEN);

		tmp[1]=0;
		m_adapter[i].descr[0]=0;
		for (int j = 0; j < (int) m_adapter[i].IfRow->dwDescrLen; j++)
		{
			tmp[0]=_mbbtombc(m_adapter[i].IfRow->bDescr[j]);
			strcat(m_adapter[i].descr,tmp );
		}

		m_adapter[i].ID=m_adapter[i].IfRow->dwIndex;
	}
	return true;
}
/////////////////////////////////////////////////////

int NetworkAdapter::GetAdapterCount()
{
	return m_index;
}
char* NetworkAdapter::GetAdapterName(int index)
{
	if(index >= m_index) return NULL;
	return m_adapter[index].name;
}
char* NetworkAdapter::GetAdapterDescription(int index)
{
	if(index >= m_index) return NULL;
	return m_adapter[index].descr;
}
DWORD NetworkAdapter::GetAdapterID(int index)
{
	if(index >= m_index) return NULL;
	return m_adapter[index].ID;
}
bool NetworkAdapter::EnableAdapter(int index,bool enable)
{
	bool setit=true;
	if(index >= m_index) return false;
	if(enable)
	{
		if(m_adapter[index].IfRow->dwAdminStatus==MIB_IF_ADMIN_STATUS_UP) setit=false;
		m_adapter[index].IfRow->dwAdminStatus=MIB_IF_ADMIN_STATUS_UP;
	}
	else
	{
		if(m_adapter[index].IfRow->dwAdminStatus==MIB_IF_ADMIN_STATUS_DOWN) setit=false;
		m_adapter[index].IfRow->dwAdminStatus=MIB_IF_ADMIN_STATUS_DOWN;
	}
	if(setit) if(NO_ERROR!=SetIfEntry(m_adapter[index].IfRow) ) return false;
	return true;
}
bool NetworkAdapter::EnableAdapter(char *name,bool enable)
{
	for (int i=0;i<m_index;i++)
	{
		if(strcmp(m_adapter[i].name,name)==0)
		{
			if(EnableAdapter(i,enable) ) return true;
		}
	}
	return false;
}
bool NetworkAdapter::EnableAdapterID(DWORD ID,bool enable)
{
	for (int i=0;i<m_index;i++)
	{
		if(m_adapter[i].ID==ID)
		{
			if(EnableAdapter(i,enable) ) return true;
		}
	}
	return false;
}
bool NetworkAdapter::EnableAdapterDescription(char *descr,bool enable)
{
	for (int i=0;i<m_index;i++)
	{
		if(strcmp(m_adapter[i].descr,descr)==0)
		{
			if(EnableAdapter(i,enable) ) return true;
		}
	}
	return false;
}

happy day