You don't mention if your SQL Server Express is at SP1 or not. It needs to
be at least SP1 to be Vista compatible.
Check here for information on running SQL Server on Vista (and Longhorn too)
[url]http://www.microsoft.com/sql/howtobuy/sqlonvista.mspx[/url]

"Stig Kulvedrøsten" <stig@spire.as> wrote in message
news:303DE039-9A93-4FDD-8E39-270129DAFA20@microsoft.com...[color=blue]
> Using Windows Visat RTM, Visual Studio .Net 2005 SP1 and SQL Server
> Express SP
>
> When trying to run a website that uses a attachdb file in the
> connectionstring I get this error:
> An attempt to attach an auto-named database for file
> e:\website\site1\app_data\site_db.mdf failed. A database with the same
> name exists, or specified file cannot be opened, or it is located on UNC
> share.
>
> I've tried giving it admin rights and taking ownership, but no difference.
> I also get 'access denied' when trying to copy, delete and so on in
> Windows Explorer.
>
> Any suggestions?
>
> Stig
>[/color]