Got the same problem. Finally found a workaround from http://connect.microsoft.com/SQLServer/feedback/ViewFeedback.aspx?FeedbackID=435855. You have to run the sql server service as a user different from Network service. This may cause other problems later... but at least the FILESTREAM-enabled database can be created and we can go on to create tables and data and learn this new feature.
devMomentum
2009-08-23 17:48:59