Out of the box, DNN 4.0 Search is broken. A search test showed the following:

In the Log Viewer I see the following errors:
ModuleId: -1
ModuleDefId: -1
FriendlyName:
ModuleControlSource:
AssemblyVersion: 04.00.00
Method: System.Web.UI.Util.CheckVirtualFileExists
FileName:
FileLineNumber: 0
FileColumnNumber: 0
PortalID: 0
PortalName: My Website
UserID: 1
UserName: host
ActiveTabID: 37
ActiveTabName: Search Results
AbsoluteURL: /Default.aspx
AbsoluteURLReferrer:
ExceptionGUID: d7404334-fde9-4910-adea-52b19d7d8278
DefaultDataProvider: DotNetNuke.Data.SqlDataProvider, DotNetNuke.SqlDataProvider
InnerException: The file '/DesktopModules/SearchResults/SearchResults.ascx' does not exist.
Message: DotNetNuke.Services.Exceptions.ModuleLoadException: The file '/DesktopModules/SearchResults/SearchResults.ascx' does not exist. ---> System.Web.HttpException: The file '/DesktopModules/SearchResults/SearchResults.ascx' does not exist. at System.Web.UI.Util.CheckVirtualFileExists(VirtualPath virtualPath) at System.Web.Compilation.BuildManager.GetVPathBuildResultInternal(VirtualPath virtualPath, Boolean noBuild, Boolean allowCrossApp, Boolean allowBuildInPrecompile) at System.Web.Compilation.BuildManager.GetVPathBuildResultWithNoAssert(HttpContext context, VirtualPath virtualPath, Boolean noBuild, Boolean allowCrossApp, Boolean allowBuildInPrecompile) at System.Web.UI.TemplateControl.LoadControl(VirtualPath virtualPath) at System.Web.UI.TemplateControl.LoadControl(String virtualPath) at DotNetNuke.UI.Skins.Skin.InjectModule(Control objPane, ModuleInfo objModule, PortalSettings PortalSettings) --- End of inner exception stack trace ---
StackTrace:
Source:
Server Name: BARNEY
I have confirmed that '/DesktopModules/SearchResults/SearchResults.ascx does not exist and have yet to find where it's real location is.
ModuleId: -1
ModuleDefId: -1
FriendlyName:
ModuleControlSource:
AssemblyVersion: 04.00.00
Method: System.Web.UI.UserControl.get_Request
FileName:
FileLineNumber: 0
FileColumnNumber: 0
PortalID: 0
PortalName: My Website
UserID: 1
UserName: host
ActiveTabID: 37
ActiveTabName: Search Results
AbsoluteURL: /Default.aspx
AbsoluteURLReferrer:
ExceptionGUID: 761ae1d9-b426-4dee-af03-f371eb81af25
DefaultDataProvider: DotNetNuke.Data.SqlDataProvider, DotNetNuke.SqlDataProvider
InnerException: Object reference not set to an instance of an object.
Message: DotNetNuke.Services.Exceptions.ModuleLoadException: Object reference not set to an instance of an object. ---> System.NullReferenceException: Object reference not set to an instance of an object. at System.Web.UI.UserControl.get_Request() at DotNetNuke.Entities.Modules.PortalModuleBase.get_IsEditable() at DotNetNuke.UI.Containers.Title.CanEditModule() in D:\Venexus\DNN4.0\Admin\Containers\Title.ascx.vb:line 52 at DotNetNuke.UI.Containers.Title.Page_Load(Object sender, EventArgs e) in D:\Venexus\DNN4.0\Admin\Containers\Title.ascx.vb:line 82 --- End of inner exception stack trace ---
StackTrace:
Source:
Server Name: BARNEY
ModuleId: -1
ModuleDefId: -1
FriendlyName:
ModuleControlSource:
AssemblyVersion: 04.00.00
Method: DotNetNuke.UI.Utilities.DNNClientAPI.EnableMinMax
FileName:
FileLineNumber: 0
FileColumnNumber: 0
PortalID: 0
PortalName: My Website
UserID: 1
UserName: host
ActiveTabID: 37
ActiveTabName: Search Results
AbsoluteURL: /Default.aspx
AbsoluteURLReferrer:
ExceptionGUID: c9460ab3-3704-4c8b-a55d-d0d63a4a1bea
DefaultDataProvider: DotNetNuke.Data.SqlDataProvider, DotNetNuke.SqlDataProvider
InnerException: MinMax persistance type of cookie requires a ModuleId
Message: DotNetNuke.Services.Exceptions.ModuleLoadException: MinMax persistance type of cookie requires a ModuleId ---> System.Exception: MinMax persistance type of cookie requires a ModuleId at DotNetNuke.UI.Utilities.DNNClientAPI.EnableMinMax(Control objButton, Control objContent, Int32 intModuleId, Boolean blnDefaultMin, String strMinIconLoc, String strMaxIconLoc, MinMaxPersistanceType ePersistanceType, Int32 intAnimationFrames) at DotNetNuke.UI.Containers.Visibility.Page_Load(Object sender, EventArgs e) in D:\Venexus\DNN4.0\Admin\Containers\Visibility.ascx.vb:line 216 --- End of inner exception stack trace ---
StackTrace:
Source:
Server Name: BARNEY
After further research I found a fix on ecktwo's website: DNN Search for 4.0.0
UPDATE: This issue was fixed in DNN 4.0.1 release