I tried to remove 2 lines as suggested but experience the below error


Environment Information : 
System : Linux-2.6.32-27-generic-x86_64-with-Ubuntu-10.04-lucid
OS Name : posix
Distributor ID:	Ubuntu
Description:	Ubuntu 10.04.1 LTS
Release:	10.04
Codename:	lucid
Operating System Release : 2.6.32-27-generic
Operating System Version : #49-Ubuntu SMP Thu Dec 2 00:51:09 UTC 2010
Operating System Architecture : 64bit
Operating System Locale : vi_VN.UTF8
Python Version : 2.6.5
OpenERP-Client Version : 6.0.0-rc1-1
Last revision No. & ID :1738 <email address hidden>
Traceback (most recent call last):
  File "/home/phongnt/Documents/Projects/openerp-trunk/server/bin/netsvc.py", line 489, in dispatch
    result = ExportService.getService(service_name).dispatch(method, auth, params)
  File "/home/phongnt/Documents/Projects/openerp-trunk/server/bin/service/web_services.py", line 598, in dispatch
    res = fn(db, uid, *params)
  File "/home/phongnt/Documents/Projects/openerp-trunk/server/bin/osv/osv.py", line 122, in wrapper
    return f(self, dbname, *args, **kwargs)
  File "/home/phongnt/Documents/Projects/openerp-trunk/server/bin/osv/osv.py", line 176, in execute
    res = self.execute_cr(cr, uid, obj, method, *args, **kw)
  File "/home/phongnt/Documents/Projects/openerp-trunk/server/bin/osv/osv.py", line 167, in execute_cr
    return getattr(object, method)(cr, uid, *args, **kw)
  File "/home/phongnt/Documents/Projects/openerp-trunk/server/bin/addons/base/module/wizard/base_module_upgrade.py", line 100, in upgrade_module
    _, pool = pooler.restart_pool(cr.dbname, update_module=True)
  File "/home/phongnt/Documents/Projects/openerp-trunk/server/bin/pooler.py", line 60, in restart_pool
    return get_db_and_pool(db_name, force_demo, status, update_module=update_module)
  File "/home/phongnt/Documents/Projects/openerp-trunk/server/bin/pooler.py", line 39, in get_db_and_pool
    addons.load_modules(db, force_demo, status, update_module)
  File "/home/phongnt/Documents/Projects/openerp-trunk/server/bin/addons/__init__.py", line 869, in load_modules
    r = load_module_graph(cr, graph, status, report=report)
  File "/home/phongnt/Documents/Projects/openerp-trunk/server/bin/addons/__init__.py", line 742, in load_module_graph
    load_init_update_xml(cr, m, idref, mode, kind)
  File "/home/phongnt/Documents/Projects/openerp-trunk/server/bin/addons/__init__.py", line 633, in load_init_update_xml
    tools.convert_csv_import(cr, m, os.path.basename(filename), fp.read(), idref, mode=mode, noupdate=noupdate)
  File "/home/phongnt/Documents/Projects/openerp-trunk/server/bin/tools/convert.py", line 945, in convert_csv_import
    result, rows, warning_msg, dummy = pool.get(model).import_data(cr, uid, fields, datas,mode, module, noupdate, filename=fname_partial)
  File "/home/phongnt/Documents/Projects/openerp-trunk/server/bin/osv/orm.py", line 859, in import_data
    process_liness(self, datas, [], current_module, self._name, fields_def, position=position)
  File "/home/phongnt/Documents/Projects/openerp-trunk/server/bin/osv/orm.py", line 809, in process_liness
    res = _get_id(relation, line[i], current_module, mode)
  File "/home/phongnt/Documents/Projects/openerp-trunk/server/bin/osv/orm.py", line 726, in _get_id
    raise ValueError('No references to %s.%s' % (module, xml_id))
ValueError: No references to account.group_account_user