Were you able to confirm the service is pointing at stunnel.conf and not stunnel.cfg maybe?
> Date: Thu, 21 Aug 2014 16:43:16 -0700
> From: 541401@gmail.com
> To: stunnel-users@stunnel.org
> Subject: [stunnel-users] Stunnel Windows Server 2008 R2
> 
> I have installed stunnel 5.03 on  Windows Server 2008 R2 X64.  When I 
> run it as an application it works perfectly.  When I install and run the 
> service, it starts but the start notice window, title bar, says Stunnel 
> 5.03 win32 (not configured).  It appears that the stunnel service is not 
> reading the stunnel.conf.
> 
> If anyone has any suggestions how I can successfully run stunnel as a 
> service, I would be very appreciative.
> 
> Thank you!
> _______________________________________________
> stunnel-users mailing list
> stunnel-users@stunnel.org
> https://www.stunnel.org/cgi-bin/mailman/listinfo/stunnel-users