To manually grant access to the ASP.NET user run the application commands from the command line:
For Windows Server 2003 family systems running IIS 6.0, replace <ASP.NET User Account> with 'NT AUTHORITY\NETWORK SERVICE' in the following commands.
For all other cases replace <ASP.NET User Account> with 'MACHINENAME\ASPNET' where MACHINENAME is the name of your computer.
If you are working with the in build dev web server in vwd then enter your computername\yourusername
osql -E -S (local)\SQLExpress -Q "sp_grantlogin <ASP.NET User Account>"
osql -E -S (local)\SQLExpress -d ASPNETDB -Q "sp_grantdbaccess <ASP.NET User Account>"
osql -E -S (local)\SQLExpress -d ASPNETDB -Q "sp_addrolemember 'db_owner', <ASP.NET User Account>"
Note: The path to the osql.exe command must be located in your PATH environment variable
Hope it helps