network settings changed by another application

The other day I tried to install a router - a Belkin wireless G router F5D7230-4. It was faulty, so I took it back. I got a different one, a Belkin G wireless F5D7234-4. It worked fine. However, when I go to 'Networking' in Systems preferences, I get a pop up message saying 'Network settings changed by another application'. This is from the first router I tried setting up. I have to force quit System Pref's and cannot access anything in Networking because this message will not go away. How can I fix this?

That one is a bug with the latest security update from Apple, it affected my mac as well, but nothing has actually changed your network settings, but to get rid of the constant alert you are going to have to delete some pref files and start entering settings from scratch

Go to Library/Preferences/SystemConfiguration and delete the following ( make copies first):

com.apple.airport.preferences.plist
NetworkInterfaces.plist
preferences.plist
com.apple.nat.plist

thanks

Thank you,

That has sorted it out.

Another question, if I may: Can I use my airport Express with the Router? I would like to print wirelessly, or use Air-tunes. I plugged an ethernet cable between the router and Airport express and tried to print, but no go. The Airport express is working as the green light is on and I can detect it on my laptop. Any ideas?

You'll likely need to run Airport Utility and setup airtunes and printing for the Express.