Don't try to network activate by default, always ask user.
My company firewalls prevent network activation, so every time, it's fail, retry, then select the web activate.
Sorry you're having problems with the default activation setting. I don't think we've had a request to alter the default before and doing so would likely upset more customers than now. However, this doesn't help you so perhaps you have to activate often for some reason (normally, we wouldn't expect customers to activate more than once per year, unless they move to a different computer). If you activate frequently (though we do have a limit on activations, to deter piracy, which can be reset) could you describe your situation? Maybe we can add some kind of installation option, though I can't promise anything.