так QSettings позволяет использовать ini формат , нужно в конструктор передать правильный параметр

По поводу ошибок, то неплохобы было показать проблемный код

typedef QMap<QString, QString> type_ValueList;

class TDataFile
{
public:
	TDataFile(const QString &name = QString::null);
	~TDataFile();
........................................

protected:
........................................
	QMap<QString, type_ValueList> SectionList;          //Вот сэтим, возможно проблемма
	QMapIterator<QString, type_ValueList>	mi; //Или с этим
};

TDataFile::TDataFile(const QString &name)   //тут чтото еще надо инициализировать, для Qt 4.4
{
	setFileName(name);
}
......................................
bool TDataFile::useSection(const QString &section)
{
	mi = SectionList.find(section.toLower());          //На это ругается
	return (mi != SectionList.end());
}
......................................
bool TDataFile::openRead()
{
	if (!f.open(QIODevice::ReadOnly)) return false;
	ts.setDevice(&f);
	// prepare
	SectionList.clear();
	mi = NULL;                              //И на это тоже ругается
..............................
}
..............................

tdatafile.cpp(15) : error C2512: 'QMapIterator<Key,T>' : no appropriate default constructor available
        with [  Key=QString, T=type_ValueList  ]
tdatafile.cpp(120) : error C2679: binary '=' : no operator found which takes a right-hand operand of type 'int' (or there is no acceptable conversion)
tdatafile.cpp(200) : error C2679: binary '=' : no operator found which takes a right-hand operand of type 'QMap<Key,T>::iterator' (or there is no acceptable conversion)
        with [ Key=QString, T=type_ValueList ]
tdatafile.cpp(201) : error C2678: binary '!=' : no operator found which takes a left-hand operand of type 'QMapIterator<Key,T>' (or there is no acceptable conversion)
        with [ Key=QString, T=type_ValueList ]
tdatafile.cpp(207) : error C2678: binary '==' : no operator found which takes a left-hand operand of type 'QMapIterator<Key,T>' (or there is no acceptable conversion)
        with [ Key=QString, T=type_ValueList ]
tdatafile.cpp(209) : warning C4172: returning address of local variable or temporary
tdatafile.cpp(215) : error C2678: binary '==' : no operator found which takes a left-hand operand of type 'QMapIterator<Key,T>' (or there is no acceptable conversion)
        with [ Key=QString, T=type_ValueList ]