This type error is recorder every time I try to access settings (module, page, admin, or host) from 2 of the 11 portals I have in this DNN instance. The only thing I see may be different is the skin. I did replace the default skin through one of the working portals via  portals/site admin no change. 

Any ideas will be greatly appreciated thank you in advance.

ModuleControlSource: Admin/Portal/SiteSettings.ascx
AssemblyVersion: 04.09.04
PortalID: 63
PortalName: La Cascia's Bakery
UserID: 2263
UserName: Lacasciasbakery
ActiveTabID: 2409
ActiveTabName: Site Settings
RawURL: /Admin/SiteSettings/tabid/2409/Default.aspx
AbsoluteURL: /Default.aspx
AbsoluteURLReferrer: http://lacasciasbakery.com/Admin/LogViewer/tabid/2418/Default.aspx
UserAgent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:16.0) Gecko/20100101 Firefox/16.0
DefaultDataProvider: DotNetNuke.Data.SqlDataProvider, DotNetNuke.SqlDataProvider
ExceptionGUID: e277372b-8611-4071-9d71-d9b86bee83db
InnerException: C:\Inetpub\wwwroot\2.egb3.com\Admin\Portal\sitesettings.ascx(160): error BC30560: 'controls_skincontrol_ascx' is ambiguous in the namespace 'ASP'.
FileName:
FileLineNumber: 0
FileColumnNumber: 0
Method: System.Web.Compilation.BuildManager.CompileWebFile
StackTrace:
Message: DotNetNuke.Services.Exceptions.ModuleLoadException: C:\Inetpub\wwwroot\2.egb3.com\Admin\Portal\sitesettings.ascx(160): error BC30560: 'controls_skincontrol_ascx' is ambiguous in the namespace 'ASP'. ---> System.Web.HttpCompileException: C:\Inetpub\wwwroot\2.egb3.com\Admin\Portal\sitesettings.ascx(160): error BC30560: 'controls_skincontrol_ascx' is ambiguous in the namespace 'ASP'. at System.Web.Compilation.BuildManager.CompileWebFile(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.Compilation.BuildManager.GetVPathBuildResult(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 ---
Source:

What I mean is: each portal URL/http alias is running under its own IIS instance and each IIS instance uses the same home directory.  for example each each IIS instance relative to this DNN uses the same C:\Inetpub\wwwroot\DNN3 as the home directory. The modules versions are the same for all the websites that share the same home directory.

I have been running like this for years, primarily to separate URL's and assign individual SSL certificates, and that is because I only use one IP address, one DNN instance, and multiple Websites per customer.

To eliminate  the possibility of conflict I will start a parallel site on separate database and web servers and include all the http alias into one IIS instance with all portal alias.

By the way, as you can tell this is an old DNN instance one of my first attempts in DNN. I have changed my MO to a more practical and maintainable way.

Thank you again for all you support.