First of all, you need to make sure that your router supports Port Mapping, and that you are not on a password-protected wireless network.
On the Skype Home support page, it appears that other people are having the same problem, although only with Skype 5.2 and 5.3. As they don't have any solution, I am guessing that it does not have to do with your IE settings.
However, what I would do is the following:
- Save your current IE/Skype settings.
- Revert all of the above settings to their default state, and see if Skype Home works then. If not, then it is a problem with Skype, not you.
- If it does work, you have at least two options. One, you can use debugging applications to track the requests and URI's that Skype requests, and add any needed exceptions. Another alternative (or at the same time) is to progressively re-enable your Skype/IE lockdown settings one at a time, and use trial-and-error to figure out the settings.
You could also try to talk to a Skype engineer/programmer, but I doubt you'd get very far ;)