I downloaded and ran the windows binary 4.33. When I use the stunnel.pem it runs fine as a service.
I created my own pem ( using Openssl on OpenSolaris ) and it won't run now as a service. I get a timeout message.
If I then uninstall it as a service, and run it as an application, it works.
Ideas on getting to run as a service with my pem? The log says nothing of note.
Is SYSTEM the owner of your pem file? I don't know for sure with stunnel, but I've set up autossh as a system service in Cygwin, and for that to work SYSTEM has to be the owner of any ssh keys, or the service fails with obscure error messages.
Good luck, Andrew.