Apologies, I should have elaborated a bit more on the issues.
The site renders partially, looks like all the HTML content works fine. Images, Script Files and some style sheets don't seem to load. The link to login still appears and the login form renders fine which is how I am able to login. Once logged in, all the images, scripts and style sheets load properly and I am able to browse the site. If I then log out, I can browse the site unauthenticated most likely because all the resources are cached. If i clear my cache, the issue returns.
If enter the URL http://www.mysite.com, I am immediately directed to /login.aspx?ReturnURL=%2f. I then get a message saying that the page cannot be found. When I click on my "Sign-In" link, I'm taken to /Secure/Login.aspx?returnurl=/Default.aspx. The login form renders correctly (no images still) and I'm able to login. Once logged in, I'm taken to the home page of the site and page looks exactly as it's supposed too.
In the MojoPortal log, there are the following entries (3 extracted):
2017-03-15 19:01:08,716 ERROR 174.2.181.204 - en-CA - /login.aspx?ReturnUrl=%2fData%2fSites%2f1%2fImages%2fHeader%2fbanner2b.jpg - mojoPortal.Web.PageNotFoundHttpModule - Referrer(http://www.mysite.com/Secure/Login.aspx?returnurl=/Default.aspx) PageNotFoundHttpModule handled error.
System.Web.HttpException (0x80004005): The file '/login.aspx' 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, 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.Compilation.BuildManager.GetVirtualPathObjectFactory(VirtualPath virtualPath, HttpContext context, Boolean allowCrossApp, Boolean throwIfNotFound)
at System.Web.Compilation.BuildManager.CreateInstanceFromVirtualPath(VirtualPath virtualPath, Type requiredBaseType, HttpContext context, Boolean allowCrossApp)
at System.Web.UI.PageHandlerFactory.GetHandlerHelper(HttpContext context, String requestType, VirtualPath virtualPath, String physicalPath)
at System.Web.UI.PageHandlerFactory.GetHandler(HttpContext context, String requestType, String virtualPath, String path)
at System.Web.HttpApplication.MaterializeHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute()
at System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously)
2017-03-15 19:01:08,736 ERROR 174.2.181.204 - en-CA - /login.aspx?ReturnUrl=%2fdata%2fstyle%2fnivoslider%2fnivo-slider.css - mojoPortal.Web.PageNotFoundHttpModule - Referrer(none) PageNotFoundHttpModule handled error.
System.Web.HttpException (0x80004005): The file '/login.aspx' 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, 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.Compilation.BuildManager.GetVirtualPathObjectFactory(VirtualPath virtualPath, HttpContext context, Boolean allowCrossApp, Boolean throwIfNotFound)
at System.Web.Compilation.BuildManager.CreateInstanceFromVirtualPath(VirtualPath virtualPath, Type requiredBaseType, HttpContext context, Boolean allowCrossApp)
at System.Web.UI.PageHandlerFactory.GetHandlerHelper(HttpContext context, String requestType, VirtualPath virtualPath, String physicalPath)
at System.Web.UI.PageHandlerFactory.GetHandler(HttpContext context, String requestType, String virtualPath, String path)
at System.Web.HttpApplication.MaterializeHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute()
at System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously)
2017-03-15 19:01:08,862 ERROR 174.2.181.204 - en-CA - /login.aspx?ReturnUrl=%2fData%2fSites%2f1%2fImages%2flogo1.png - mojoPortal.Web.PageNotFoundHttpModule - Referrer(http://www.mysite.com/Secure/Login.aspx?returnurl=/Default.aspx) PageNotFoundHttpModule handled error.
System.Web.HttpException (0x80004005): The file '/login.aspx' 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, 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.Compilation.BuildManager.GetVirtualPathObjectFactory(VirtualPath virtualPath, HttpContext context, Boolean allowCrossApp, Boolean throwIfNotFound)
at System.Web.Compilation.BuildManager.CreateInstanceFromVirtualPath(VirtualPath virtualPath, Type requiredBaseType, HttpContext context, Boolean allowCrossApp)
at System.Web.UI.PageHandlerFactory.GetHandlerHelper(HttpContext context, String requestType, VirtualPath virtualPath, String physicalPath)
at System.Web.UI.PageHandlerFactory.GetHandler(HttpContext context, String requestType, String virtualPath, String path)
at System.Web.HttpApplication.MaterializeHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute()
at System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously)
2017-03-15 19:01:08,943 ERROR 174.2.181.204 - en-CA - /login.aspx?ReturnUrl=%2fData%2fSites%2f1%2fImages%2fHeader%2fbanner1b.jpg - mojoPortal.Web.PageNotFoundHttpModule - Referrer(http://www.mysite.com/Secure/Login.aspx?returnurl=/Default.aspx) PageNotFoundHttpModule handled error.
System.Web.HttpException (0x80004005): The file '/login.aspx' 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, 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.Compilation.BuildManager.GetVirtualPathObjectFactory(VirtualPath virtualPath, HttpContext context, Boolean allowCrossApp, Boolean throwIfNotFound)
at System.Web.Compilation.BuildManager.CreateInstanceFromVirtualPath(VirtualPath virtualPath, Type requiredBaseType, HttpContext context, Boolean allowCrossApp)
at System.Web.UI.PageHandlerFactory.GetHandlerHelper(HttpContext context, String requestType, VirtualPath virtualPath, String physicalPath)
at System.Web.UI.PageHandlerFactory.GetHandler(HttpContext context, String requestType, String virtualPath, String path)
at System.Web.HttpApplication.MaterializeHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute()
at System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously)
The above 3 entries exist for every image or resource file associated with the site. These errors stop once logged in.
I hope this helps in finding the cause.