Problem with installation of NAV 2009 DEMO

Hi All

I get the error below when i'm trying to install the demo of NAV2009:

Microsoft Dynamics NAV 2009 Build 27808
Error Report
SQL Server option
Microsoft Dynamics NAV 2009 Components for Microsoft SQL Server
Fatal error during installation.

Error -2147217865: failed to execute SQL string, error detail: Invalid object name 'master.sys.objects'., SQL key: DropXpNdoGroups SQL string: IF EXISTS (SELECT * FROM [master].[sys].[objects] WHERE name = 'xp_ndo_enumusergroups') EXEC sp_dropextendedproc xp_ndo_enumusergroups
Cronus Sample Database for Microsoft Dynamics NAV 2009
Fatal error during installation.

Error -2147217865: failed to execute SQL string, error detail: Invalid object name 'master.sys.databases'., SQL key: StopIfDatabaseExist SQL string: IF EXISTS (SELECT * FROM [master].[sys].[databases] WHERE name = 'Demo Database NAV (6-0)') RAISERROR (N'A database with name %s already exists.',20,1,'Demo Database NAV (6-0)') WITH LOG

Hope anyone can help. THANKS