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Depending on what ISP you're using, this may not be possible. Follow the steps suggested above although http should be the only one needed. You need to be able to ping your domain and resolve to your ip (for example, if your ip was 126.96.36.199 and your domain was google.com, a ping in command prompt to google.com should resolve to 188.8.131.52). Once that is done, then the domain is forwarding to the correct IP. If this is not done, then you cannot do much more on troubleshooting. You can test to see if your ISP allows it by forwarding your ports to your http server and trying to access it via ip from outside of that network. edit: walked away for lunch and someone beat me to it!
IP Route fixes the issue with the seperate subnets on a single nic. You can add up to 127 different ip's all having different subnets in 2003 (maybe more now). It sounds like your DC may be foobared. You may try and bring up another box to promote it as a bdc and see if your gpo/dns settings replicate to it. You're probably going to have to go through each event in ev and start by fixing one by one. If you can post a few of the errors, there might be more detailed info on troubleshooting it.