Does that particular user have any other processes running?

I have seen in the past where a user was connected via SSMS and the Application showed as Microsoft SQL Server. The user ended up with a couple of spids, 1 in master and 1 in the user database. When the user disconnected and logged off - the user database spid went away but the spid in master remained.

What is the last batch time stamp of that user? How long ago did the user login to the db? Can you go and ask the user, or is it a service account or generic account?

I like to use the following query in conjunction with sp_who2 to find a little more detail on the running queries.

select percent_complete, estimated_completion_time, cpu_time/60000 as CPUMinutes, total_elapsed_time/60000 as TotalMinutes,session_id

,start_time,command, st.*,sql_handle,plan_handle,database_id,wait_time,last_wait_type

,wait_resource,transaction_id,reads,writes,logical_reads

from sys.dm_exec_requests r

cross apply sys.dm_exec_sql_text(sql_handle) AS st