Deleting folder results in application crash

[testus]

Everytime I call QDir::removeRecursively() my application crashes AFTER having removed the folder containing the files correctly.
Having done some testing I found out that it depends on how I call the function. This is my code:

Recorder::Recorder(ParentClass *parent): QObject(parent){
	
	 connect(this,SIGNAL(finishedRec(QString,QString)),this,SLOT(finishedRecording(QString,QString)));
}

void Recorder::start(){
	if (!recording){
                    recording=true;
		recThread.reset(new std::thread(&Recorder::recordThread, this));
	}
}

void Recorder::stop(){
	recording = false;
	recThread->join(); recThread.reset();
}
void Recorder::recordThread(){
	QString picDir;
	QString filename;
	//....
	while(recording){
		//writing frames to folder
	}    
	emit finishedRec(picDir,filename);    
}

void Recorder::finishedRecording(QString picDir, QString filename){
	QProcess* proc = new QProcess();
	vecProcess.append(proc);
	vecString.push_back(picDir);
	proc->start("C:\\ffmpeg.exe", QStringList() <<"-i"<< picDir << "-r"<< "30" << "-vcodec"<< "ffv1" << filename);
	connect(proc,SIGNAL(finished(int)),this,SLOT(finishedProcess()));
}

void Recorder::finishedProcess(){
	for (int i=0; i<vecProcess.size();i++){
		if(vecProcess.at(i)->state()==QProcess::NotRunning){
			delete vecProcess.at(i);
			vecProcess.erase(vecProcess.begin() + i);

			QString folderToRemove=vecString.at(i);
			folderToRemove.chop(12);
			qDebug() << folderToRemove;
			QDir dir(folderToRemove);
			dir.removeRecursively();
			vecString.erase(vecString.begin() + i);

		}
	}
}

Only if I leave dir.removeRecursively() in, my application will always crash. Without it everything works as intended. Even deleting all the files with

QDir dir(path);
dir.setNameFilters(QStringList() << "*.*");
dir.setFilter(QDir::Files);
foreach(QString dirFile, dir.entryList()){
	dir.remove(dirFile);
}

will cause a crash AFTRER all the files were deleted.

Calling removeRecursively() in a different event loop works. Why doesn't it work when using it in a SLOT like shown in my example?