I try to install the last version from 6 days and allways get the same error (above). I have been read a lot of soluctions but cant make it work. Is there any special configuration? I think the problem is with my ASPNET user. I check mu database and ASPNET is the owner of it.  Importante, i am not make a upgrade, i try to install on a new machine.

• I gave full access to site directory to ASPNET.
• I check the ASPNET access to DB. He is owner!
• I check the web config but can´t change the password for SQL Express! (I don´t know how)

Connection Error(s):
Index #: 0
Source: .Net SqlClient Data Provider
Class: 11
Number: 4064
Message: Cannot open user default database. Login failed.

Index #: 1
Source: .Net SqlClient Data Provider
Class: 14
Number: 18456
Message: Login failed for user 'SOFT2\ASPNET'.

Anyone can help me?

I have same problem ... now...first I tried to just install DNN always leaving everything as it is by default and it worked out it got installed, then I have made a mistake that I couldn't fix so I removed DNN  and started to setup again from the begining... this time I decided to read what I am clicking ok  ( next )  to... well at the point where I had to Configure Database Connection I decided to enter my real DB name  and if I keep check on Integrated Security I get  same 2 errors as topicstarter, if I uncheck that point (Integrated Security ) and fill in my login and password that I use to loginto the windows I get

Connection Error(s):
Index #: 0
Source: .Net SqlClient Data Provider
Class: 14
Number: 18456
Message: Пользователю "JULIA\Admin" не удалось войти в систему.

it is strange firstly because I use integrated security  and when I open mssql server management studio express I don't have to write any passwords, it uses the one I have already entered when I was entering my windows ( as I understand )

now I will try to answer your  questions

are you using sql express connection string with .mdf specification?

I don;t really know what you mean here ( sorry )

which OS are you using?  - WINXP SP2

did you install sql express advanced with Database Management Studio -yes

thу funny part is that I had it installed today when I was not  reading or filling anything out just clicking next next next ... and now when I decided to read and do the right way I can't seems to get it right :)

PS and it proved again  if I keep SQL Server 2005 (Express) File and DB name by default "Database.mdf " everything passes succesfully but it is not the name of my database! ( yes I have just yet again  kept everything as it was by default and pressed next.... and it went on with the installation process....

PPS.... well now I tried again what I did was I went to SQL management studio express and connected that database that is in App_Data of DNN .. then tried to install again and to my surprise now I get these 2 errors

Connection Error(s):
Index #: 0
Source: .Net SqlClient Data Provider
Class: 11
Number: 4064
Message: Невозможно открыть пользовательскую базу данных по умолчанию. Не удалось выполнить вход.

Index #: 1
Source: .Net SqlClient Data Provider
Class: 14
Number: 18456
Message: Пользователю "JULIA\ASPNET" не удалось войти в систему.
 with by default settings ! so it all has to do with the database and it's connection to SQL management studio express ....

( sorry I have written so much trash  here, I am not a programmer and I was trying to install DNN  by tutorial... so I have no  idea of what I am doing..... so I am writing everyting down .... maybe it will help to resolve our problems