Issues I need to resolve

I need to post for a while about some issues I am having on the network and the steps that I take to try and figure them out/solve them.

DNS Issues
To tell the truth, I am not sure I am having DNS issues, but something smells odd. Here is what I see that worries me:
1. Can no longer get to the DNS mmc on my server (this may be a permissions issue)
2. A tracert on my PC to anything offnetwork fails EVERYTIME (have tested another PC here on same subnet and see the same behavior)
3. NSLOOKUP returns a non-authoritative answer everytime and doesn't find internal addresses ever

Switch Issues
Suddenly this week, I can't access my main switch. I have tried the web interface and telnet. I used this a couple of months ago to update the software, but now I can't get into it for anything. It seems to be working normally.

What is THIS?
I have an unknown device, which I have to assume is our second router on our network, that no one knows anything about. We had a consultant come and he wanted to know what this was, I couldn't tell him. What I do know is that traffic that travels from our 10/1000 subnet to our 10/100 subnet is SLLLOOOOWWW