If you probably have problems with special chars within the Productsearch during Quote/Invoice Generation, you could do this small modification:
I think the reason why this could happen, is the encoding of entities within the database class.
Search
$result[] = array('label'=>decode_html($recordModel->getName()), 'value'=>decode_html($recordModel->getName()), 'id'=>$recordModel->getId());
Replace with
$result[] = array('label'=>decode_html(decode_html($recordModel->getName())), 'value'=>decode_html($recordModel->getName()), 'id'=>$recordModel->getId());