Well... can't say I'm impressed with DNN installation procedure: installing latest stable version on a SQL Server 2005 is proving to be unnecessarily painful (I wonder why setting up any PHP+MySQL solution is a breeze in comparison - well, actually also in absolute terms).

Anyways, here are the facts:

INSTALLATION DETAILS

• DNN 4.9.3
• Windows Server 2008 with .NET 2.0 and SQL Server 2005 (9.0.3042)
• SQL Server connection settings (Server IP, DB Name, Username & Password) tested successfully by connecting to the DB via MS SQL Manager Express - account used is confirmed being owner of the DB in the DB Properties window

THE STORY SO FAR

1. copied all the files in the http root folder of  the webserver
2. applied all the correct permissions (NETWORK SERVICE account has full control over the folder structure)
3. DNN initial setup screen shows up: I select Custom Install (tried with Typical too, no change) and then Next
4. Checking File Permissions screen shows up: clicking Test Permissions returns Your site passed the permission check - I select Next
5. Configure Database Connection screen shows up: I tried basically all possible combinations on this screen, best results are obtained by using these settings:
   - SQL Server 2000/2005/2008 Database
   - Server: [IP of the server] (same as in MS SQL Manager Express)
   - Database: [DB name] (same as in MS SQL Manager Express)
   - Integrated Security: Unchecked
   - User ID: [Username] (same as in MS SQL Manager Express)
   - Password: [Password] (same as in MS SQL Manager Express)
   - Run as DB Owner: Checked
   - Object Qualifier: DNN_ (also tried with empty, no change)
    
6. Clicking Test Database Connection returns Connection Success: I click Next

7. Run Database Installation Scripts screen shows up, Installing Database Scripts bar filling up... After 5/10 seconds the log window shows:
   
   Installing Database - Version 0.0.0...Success
   Installing Database - Version 0.0.0...FAILURE 400 - Violation of UNIQUE KEY constraint 'IX_DNN_Version'. Cannot insert duplicate key in object 'dbo.DNN_Version'.%0d%0aThe statement has been terminated.
   
   Apart from the fact that the DB version is labelled 0.0.0, the same operation (Installing Database - Version 0.0.0) is reported as being both successful AND failed: wth?!?

8. Installation stops here: MS SQL Manager Express shows that many DB objects have been created at apparently no avail.

Is anyone else having these issues?

Hey mikevdm, thanks for your reply.

I thought that as well: since the first reinstallation, I've always taken care of manually deleting the objects in the SQL Server - only problem is, I'm not really 100% sure I'm getting all of them... Unfortunately I'm not SA, so I can only tinker inside my own DB and I cannot delete it and recreate it from scratch.

Therefore, what I'm doing between the (countless) failed installations is manually deleting these objects:

• Database Diagrams: none (this collection is empty anyways)
• Tables: all of them (except for the System Tables)
• Views: all of them (except for the System Views)
• Synonyms: none (this collection is empty anyways)
• Stored Procedures: all of them (except for the System Store Procedures)
• Functions: none
• Database triggers: none (this collection is empty anyways)
• Assemblies: none (this collection is empty anyways)
• Types: none
• Rules: none (this collection is empty anyways)
• Default values: none (this collection is empty anyways)
• Users: none
• Database roles: all the roles having the aspnet_ prefix
• Application roles: none (this collection is empty anyways)
• Schemas: all the schemas having the aspnet_ prefix
• Symmetric keys: none (this collection is empty anyways)
• none (this collection is empty anyways)
• Certificates: none (this collection is empty anyways)

This is all very frustrating... Is it possible that no one knows what the problem could be? I mean, I've followed all the instructions I could find regarding the installation procedure, and from what I can understand all the variables in play are pretty standard - server type, DNN version, etc.
How's it possible that the installation simply fails with no solution?

Now I understand why people are generally skeptical regarding ASP.NET + MS SQL... :(
 

I haven't seen your whole thread but I've installed a number of 4.9.3 installs from scratch without a problem.