Heap corruption detected while freeing memory

[forstudy3]

I have following code in which I am getting "Heap corruption detected" message while trying to freeing memory allocated while using strdup().

#include <iostream>
#include <string>
#include "Check.h"


static void main()
{

	
for (int i = 0;i< 5 ;i++)
{
char cname[32];
cname = GetGroupName()//These function assigns name here
bool exist;
	exist =	GetGroupStatus(cname);
}

}

bool GetGroupStatus(char *cname)
{
	char * cTemp = NULL;
	cTemp = _strdup(cname);
	bool bGrpStatus; 
	size_t found;

	//some code here

	std::string sTemp = cTemp;
	
	found = sTemp.find("GROUP");

	if (found != string::npos)
		bGrpStatus = true;
	else
		bGrpStatus = false;

	if (cTemp  != NULL)
	free(cTemp);	//These causes heap corruption detected message when control comes here second time

	return bGrpStatus; 
}

Please let me know what I am missing?