One more funny thing with LLAWP. If you see http 500 error from your siteminder isapi filter on IIS and there is such error message in a Windows machine event log
Failed to Start the LLAWP process. CreateProcess Failed. Check that LLAWP.exe is in your system path.
It means that you did not reboot the machine after you had installed Siteminder on it. <sarcasm>The event log message is very obvious and relates closely to the solution, doesn’t it?</sarcasm>