Lotus Notes Single Signon Failure
It has been a long time since I posted, but came across this bizarre fix for Lotus Notes Single Signon failures. I had uninstalled Lotus Notes completely on my machine (Deleted registry entries, removed directories, etc) and reinstalled Lotus Notes 8.5.2 All clients (Designer, Admininstrator, Client). For some reason, my single signon stopped working. I found this tech note from IBM.
In summary, here is what you should check: