Updating this further...
I uninstalled and deleted all traces of the Solpart menu and also the old DNN Survey module, and also an old skin that was not in use but had a container with a solpart menu reference.
With all of the above gone and a fresh upgrade, I still get the same issue... no login box.
I've wiped the events and restarted to ensure I get the error that specifically related to this from the log:
The base class includes the field 'ctlProfile', but its type (DesktopModules.Admin.Security.DNNProfile) is not compatible with the type of control (ASP.desktopmodules_admin_security_profile_ascx).
at System.Web.Compilation.AssemblyBuilder.AddBuildProvider(BuildProvider buildProvider)
at System.Web.Compilation.BuildProvidersCompiler.ProcessBuildProviders()
at System.Web.Compilation.BuildProvidersCompiler.PerformBuild()
at System.Web.Compilation.BuildManager.CompileWebFile(VirtualPath virtualPath)
at System.Web.Compilation.BuildManager.GetVPathBuildResultInternal(VirtualPath virtualPath, Boolean noBuild, Boolean allowCrossApp, Boolean allowBuildInPrecompile, Boolean throwIfNotFound, Boolean ensureIsUpToDate)
at System.Web.Compilation.BuildManager.GetVPathBuildResultWithNoAssert(HttpContext context, VirtualPath virtualPath, Boolean noBuild, Boolean allowCrossApp, Boolean allowBuildInPrecompile, Boolean throwIfNotFound, Boolean ensureIsUpToDate)
at System.Web.UI.TemplateControl.LoadControl(VirtualPath virtualPath)
at DotNetNuke.UI.ControlUtilities.LoadControl[T](TemplateControl containerControl, String ControlSrc)
at DotNetNuke.UI.Modules.WebFormsModuleControlFactory.CreateModuleControl(TemplateControl containerControl, ModuleInfo moduleConfiguration)
at DotNetNuke.UI.Modules.ModuleControlFactory.LoadModuleControl(TemplateControl containerControl, ModuleInfo moduleConfiguration)
at DotNetNuke.UI.Modules.ModuleHost.LoadModuleControl()
The base class includes the field 'ctlProfile', but its type (DesktopModules.Admin.Security.DNNProfile) is not compatible with the type of control (ASP.desktopmodules_admin_security_profile_ascx).
at System.Web.Compilation.BaseTemplateCodeDomTreeGenerator.BuildFieldDeclaration(ControlBuilder builder)
at System.Web.Compilation.BaseTemplateCodeDomTreeGenerator.BuildSourceDataTreeFromBuilder(ControlBuilder builder, Boolean fInTemplate, Boolean topLevelControlInTemplate, PropertyEntry pse)
at System.Web.Compilation.BaseTemplateCodeDomTreeGenerator.BuildSourceDataTreeFromBuilder(ControlBuilder builder, Boolean fInTemplate, Boolean topLevelControlInTemplate, PropertyEntry pse)
at System.Web.Compilation.BaseTemplateCodeDomTreeGenerator.BuildSourceDataTreeFromBuilder(ControlBuilder builder, Boolean fInTemplate, Boolean topLevelControlInTemplate, PropertyEntry pse)
at System.Web.Compilation.TemplateControlCodeDomTreeGenerator.BuildMiscClassMembers()
at System.Web.Compilation.BaseCodeDomTreeGenerator.BuildSourceDataTree()
at System.Web.Compilation.BaseCodeDomTreeGenerator.GetCodeDomTree(CodeDomProvider codeDomProvider, StringResourceBuilder stringResourceBuilder, VirtualPath virtualPath)
at System.Web.Compilation.BaseTemplateBuildProvider.GenerateCode(AssemblyBuilder assemblyBuilder)
at System.Web.Compilation.AssemblyBuilder.AddBuildProvider(BuildProvider buildProvider) System.Web
Any ideas still appreciated
Regards
Rob