I am using InSSIDer Office and WiSpy 2.4 atm and I have an issue with an Engenius Access Point EAP350 in a specific house. No matter what channel I choose, a non Wifi-transmitter appears exactly in my channel, its red and makes wifi traffic almost impossible. The moment I disable the Access Point the interference is gone.

If I use the Access Point in another house there is no interference.

Can somebody help me out here?