Sorry, Jim, we do not have an answer for this. The IIS installation has apparently dropped the ISAPI filter that causes IIS to compile and run ASPX pages rather than serving them as static (HTML) files. It's the same error message you would get if the .NET Framework got uninstalled or the ASP .NET feature got removed on a server 2008 system.
ANTS Profiler does configure IIS when attaching. If you are actually launching rather than attaching, there is a possibility that the configuration is not being created correctly. When profiling normally (not attaching), Profiler has to create a cut-down applicationHost.config and start w3wp.exe using that config file.
In either case, we have had no reports of this message before. We may have to continue this discussion over email so we can troubleshoot it properly.