Okay, first of all....I'm not sure whether this has anything to do with your problem; it was just a thought, so I told you to at least exclude certain possible causes......
Look at my screen shots to see what I meant.
That it reverted back to your computer name seems to be okay; I think it should be that way. have you also tried not to use manual port forward? I.e. using UPnP?? Because for manual port forwarding you should have an static IP and if you do only one slight mistake in setting up a static IP then the whole process won't work.
