The white circle usually contains a green arrow, a blue paused symbol, or a red square – indicating that the SQL Server service is either running, paused, or stopped respectively.
Usually security is set-up so that only administrators can see the service status, so regular users don’t have access to that information, hence why SSMS displays an empty white circle, meaning the service is in an indeterminate state, from its viewpoint – of course if you can connect to the service and run queries then it has to be running, so don’t worry about this.
See here: http://www.sqlservercentral.com/Forums/Topic825246-146-1.aspx