Hi, Looks like you have similar problem to me. I took my D-link routers out into back tyard and smashed them. I will never buy Dlink equipment again.
1- Installed a DIR-600 - setup page at 192.168.0.1
2- Removed DIR-600 and replaced with DSL-2730B as I wanted ADSL2. - setup page at 192.168.1.1
3- Internet would stop operating. Discovered that the setup page for DSL was replaced by that of DIR. Accessing 192.168.1.1 would show up DIR setup page instead. WTF.
4- Could not get rid of this anomaly. Smashed Dlink equipment and threw in garbage. Formatted C drive.
5- Installed C-isco Link-sys ADSL2 router. Nice unit. - setup page at 192.168.1.1
7- Anomaly appeared again, ie Internet stops and setup page at 192.168.1.1 becomes DIR-600 setup page
6- It appears that one computer on my LAN is 'infected' as if I disconnect the ethernet cable from another computer the internet computerm returns to full operation.
7- I'm about to format the c drive on that other computer.
8- Solution...NEVER buy Dlink equipment. It contains ghost software which installs on your system, takes over the address 192.168.1.1, and you can not remove it. What a disgrace. Somewhere around step 3 above Dlink support simply got me to plug my laptop onto my router and, because that seemed to work ok, the problem was therefore mine. WTF dlink?