deleting first item in a list

[soul_rebel]

i have subclasses kprocess and want to buffer output in a qstringlist.
when output is received i do this:

m1.lock();	
QStringList temp = QStringList::split('\n', QString::fromLatin1(buffer, buflen));
for ( QStringList::Iterator it = temp.begin(); it != temp.end(); ++it ) 
        mStdoutBuffer.append(*it);
	m1.unlock();

m1.lock();	
QStringList temp = QStringList::split('\n', QString::fromLatin1(buffer, buflen));
for ( QStringList::Iterator it = temp.begin(); it != temp.end(); ++it ) 
        mStdoutBuffer.append(*it);
	m1.unlock();

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and when the buffer is read this code is exeuted:

/// reads first line from Buffer and then removes it so content "moves up"
if (canReadLineStdout() && ( m1.tryLock()))
{
	QString Buffer = mStdoutBuffer.first();
	QStringList::Iterator it = mStdoutBuffer.begin();
	mStdoutBuffer.remove(*it);
	m1.unlock();
	return (Buffer);
} else 
	return ("");

/// reads first line from Buffer and then removes it so content "moves up"
if (canReadLineStdout() && ( m1.tryLock()))
{
	QString Buffer = mStdoutBuffer.first();
	QStringList::Iterator it = mStdoutBuffer.begin();
	mStdoutBuffer.remove(*it);
	m1.unlock();
	return (Buffer);
} else 
	return ("");

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but i get
QGVector::remove: Index 1343941632 out of range
QGVector::insert: Index 1343941632 out of range

what am i doing wrong? (the program mostly doesnt crash but something isnt well for sure)
thanks