cannot uninstall old internet connection information

My husband and I both run Macs, and until very recently we were BTinternet Home Hub users - both by wifi but his computer was the initial subscriber. We decided to unsubscribe from our account and cease using BT, and use wireless internet access at our friend's house where we're going to stay for a few months. He is running Safari and I am running Firefox.

I can access networks via airport, either unsecure or password protected like at my friend's house, cafes etc, but my husband cannot, as it seems his historic network information is overriding the airport. When he tries to access the internet via airport and opens Internet Connect it's clear that there's something about his network settings which is blocking access. The message is "your network settings have been changed by another application".

When we called BT about the issue they said they wouldn't give any assistance as we're not BT customers. He was advised to get rid of all BT files but dumped and deleted instead of uninstalling unfortunately.

Is the only way to reinstall the mac startup disk to wipe ths BT settings from the memory??

I hope someone can help. Thanks.

This has nothing to do with BTInternet (probably). Have you done an update recently?
Look here: Applelinks Discussion Forum | "your network settings have been changed by another application" ...

tried to fix via the tonza recommendation but still no advance

thanks for this - have worked through the suggested solutions (particularly TONZA's) and it still goes so far and pops up with the same dialog box - it's trying to configure airport that does it. I've tried deleting the system prefs and reconfiguring and also the added security of the login password to change prefs. But we still hit a wall........