This one has me stumped...
Do me a favor, though, because this is the first I've heard of someone actually switching their Application URI to a domain outside MySpace -- check to see what your app is passing as the oauth_consumer_key (it'll be in the querystring); I'm wondering it still isn't going to be your old 'www.myspace.com/[appid]'. We were told early on to use the Application URI as the Consumer Key, but I'm not sure if that's because it was a convienent place to find the thing, or because that's exactly what MySpace always uses.
And another thing; you said you're using msapp.example.com (I know it's made up), but does it actually exist? Could I, for example, type 'msapp.example.com' into my browser and hit a site? I'm wondering, too, if the 'Can't resolve...' issue might be that it doesn't think your URI actually exists.
Otherwise, I'm drawing a blank. The PHP library has been solid so far, and it's seems highly unlikely that its hardware if OAuthTool is giving you an error as well.
And to Shiela, your Application URI, two lines above where you found your Security Key (which is your Consumer Secret) is what you'd use for your Consumer Key.... At least, so far it's been...