Yesterday my system was working fine. but today my system is not getting shut down

Yesterday my system was working fine. but today my system is not getting shut down

Yesterday my system was working fine. but today my system is not getting shut down. When i give shut down it is giving the error message that 'Speed dispatcher stopped' . I am not sure that because of this my system is getting hang when i try to shut down . Please any one can help.. Thanks in advance.