Use this query in conjunction with sp_who to display running tasks and determine whether there are sessions blocking other sessions, and who is executing the query (sp_who)

SELECT command,
            r.session_id, r.blocking_session_id,
            s.text,
            start_time,
            percent_complete, 
            CAST(((DATEDIFF(s,start_time,GetDate()))/3600) as varchar) + ' hour(s), '
                  + CAST((DATEDIFF(s,start_time,GetDate())%3600)/60 as varchar) + 'min, '
                  + CAST((DATEDIFF(s,start_time,GetDate())%60) as varchar) + ' sec' as running_time,
            CAST((estimated_completion_time/3600000) as varchar) + ' hour(s), '
                  + CAST((estimated_completion_time %3600000)/60000 as varchar) + 'min, '
                  + CAST((estimated_completion_time %60000)/1000 as varchar) + ' sec' as est_time_to_go,
            dateadd(second,estimated_completion_time/1000, getdate()) as est_completion_time 
FROM sys.dm_exec_requests r
CROSS APPLY sys.dm_exec_sql_text(r.sql_handle) s
--WHERE r.command like ('%DBCC%')