You want to put the result here...? There are thousands of users in our system.

Let me explain this another way...

New Portal. When I am creating a user in CRM, I am executing a call in a webservice to add the user. Normaly the user is added.

Some times, around 100 users out of thousands, with nothing in common, cannot be created/updated. The "UserInfo newUser = UserController.GetUserByName(PortalID, username)" returns null. However, most of the times, user was created in aspnet_Users table, but not in Users table. So, I have to manualy clean all tables (membership and DNN) and then recreate the user, where it works.

After a week or so, we need to change user's password as per his request. While trying to do that, it returns null again. So, I am cleaning the tables, and recreating the user.