H!

I've implemented the EPiServerCommonIntegrationMembershipProvider as described here:
http://blog.tomstenius.com/2009/04/episerver-community-role-and-membership.html

And i've also added the module as described here:
http://blog.tomstenius.com/2009/09/windows-authentication-in-episerver.html

This works fine on my development computer, but on our production server i keep getting this error, which drive me nuts:
[InvalidOperationException: There is already an open DataReader associated with this Command which must be closed first.]
   System.Data.SqlClient.SqlInternalConnectionTds.ValidateConnectionForExecute(SqlCommand command) +2453561
   System.Data.SqlClient.SqlInternalTransaction.Rollback() +102
   System.Data.SqlClient.SqlTransaction.Rollback() +292
   EPiServer.Common.Data.DatabaseHandler.Rollback() +59
   EPiServer.Common.Security.Data.SecurityFactory.AddGroup(Group group) +2211
   EPiServer.Common.Security.SecurityHandler.AddGroup(IGroup group) +169
   EPiServer.Common.Web.Authorization.Integrator.SynchronizeUser(MembershipUser membershipUser, String password, Boolean enableCreateNew) +1984
   EPiServer.Common.Web.Authorization.IntegrationHttpModule.context_AuthenticateRequest(Object sender, EventArgs e) +238
   System.Web.SyncEventExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() +80
   System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) +171

It's clear to me the synchronization is started but then something goes wrong.. i cannot find the error.