Can you post your web.config file , specifically the Database Connections, it looks like the login credentials being passed to the database is the Machine\ASPNET account
A Standard Connection String will look like this:
Data Source=myServerAddress;Initial Catalog=myDataBase;User Id=myUsername;Password=myPassword;
If you want to use the credentials of the user accessing the web application, you should use:
Data Source=myServerAddress;Initial Catalog=myDataBase;Integrated Security=SSPI;
Note - you should disable anonymous access on the virtual directory if you would like to use a trusted connection i.e. the second one.