This error appeared when calling the site from vs 2008 a custom module in development.  I am not compiling dnn, only the custom module within a directory that resides in the desktopmodules directory.  This seems like an odd error as it has nothing to do with the custom module I was working on.  I have gone as far as to reboot the development box.  

Compiler Error Message: BC30456: 'HomeDirectoryMapPath' is not a member of 'PortalSettings'.

Source Error:

Line 98:                 sProtectedExtension = DotNetNuke.Common.Globals.glbProtectedExtension
Line 99:             End If
Line 100:            Return String.Concat(PortalSettings.HomeDirectoryMapPath, objFile.Folder, objFile.FileName, sProtectedExtension)
Line 101:        End Function
Line 102:

Source File: c:\inetpub\wwwroot\basePortDev20080321\Website\App_Code\Reports\Utilities.vb    Line: 100  

Here's a couple of possibilities to check out as the cause of an odd error such as this one:

1. Could your module have caused a namespace conflict with the core Reports module or the framework's UserControl, PortalModuleBase, or PortalSettings classes?

2. As it appears that you are creating a compiled (WAP) module, does your module project reference the installed version of the DotNetNuke.dll in the /bin folder or are you compiling against an earlier version of this .dll which might have gotten accidentally copied over the current version in the install's /bin folder. One time I had not noticed that my module's intentional reference to an earlier version of DotNetNuke.dll had set "Copy Local" to true thus overwriting the current installation version when the module was compiled - causing all sorts of odd method not found, etc. errors when the site was accessed.

3. As the core Report module was changed from a dynamically compiled (WSP) module in its earlier 04.x.x versions to a compiled (WAP) module in its recent 05.00.00 version, if you have upgraded the Reports module, its sub-folder under the site's App_Code folder should have been automatically removed.  In some cases, however, removal of this sub-folder (and the reference to it in the < codeSubDirectories > section of web.config) does not get removed and might cause problems such as this.