Hi Ujwol,
After a server reboot I appear to be hitting the HTTP handler and I am getting the HTTP_SM_USER header.
Unfortunately I am getting a SQL login failure when the handler is making a call to the DB:
Login failed for user 'NT AUTHORITY\ANONYMOUS LOGON'
The SQL credentals are all correct and have been working perfectly pre-Siteminder setup.
All of my application pools run with a specific Active Directory account and have full permissions on the IIS folders.
Is this something you would have come across before in Siteminder?