Siteminder is a solution for Single Sign On service from CA. It supports IIS web service. Siteminder can fail due to some wrong configurations or internal errors and prevent an access to your web application. Likely, you will see HTTP 500 code in your browser in this case. Then take a look at Event Viewer Application log under the ‘Siteminder’ source.
For example, you see the message “Failed to send message to the LLAWP.” LLAWP is a process which started by Siteminder. The process listens for log messages and handles them. Due to a software bug or something else this process can hang out stopping the show. The solution is simple in this case – kill the process and it will bring back in a valid state resolving the issue