ASP.NET provides good integrated services with SQL Server Database. When you we want to use the membership, profiles, roles management, personalization.. etc. We have to first create the database for those tables right. In order to create that we use the aspnet_regsql at command prompt.

C:\WINDOWS\Microsoft.NET\Framework\v2.0.50727\aspnet_regsql.exe

This is can be run in command mode and wizard mode also. I think we mostly use the wizard mode only.

We have to give the database name under which aspnetdb schema should be created and u can link it to the database directly from asp.net

Happy Coding.... :)

Reason might be, You may have installed IIS after installing .Net framework. In this case, follow below steps to resolve
Go to Visual Studio Command Prompt
Point to the framework path c:\windows\microsoft.NET\Framework\v2.0.50727\
and run the below command....

>aspnet_regIIS -i