Have you talked to the owner of this device to see if he aware of whats going on and to see if they can stop there device from trying to access the router?
Link>
Wireless Installation ConsiderationsWhat wireless modes are you using? Under Setup/Wireless/Manual.
Channel Width set for Auto 20/40Mhz or try 20Mhz only.
Try setting a manual channel to a open or unused channel. 1, 6 or 11. 11 for single mode N if the channel is clear.
What security mode are you using?
Preferred security is WPA-Personal. WPA2/AES Only. Some WiFi adapters don't support AES, so you might want to try TPIK only or Auto.
What wireless devices do you have connected?
Any cordless house phones?
Any other WiFi routers in the area? Link> Use InSSIDer to find out. How many?Turn off WISH, and WPS under Advanced.
Try turning off Short GI, WLAN Partition,and Extra Wireless Protection if you have it. Under Advanced/Advanced Wireless.
Enable
WMM Enable Under Advanced/Advanced Wireless.
You might try to set the SSID to HIDDEN and see how it goes. You'll need to ensure that your other devices can connect to the hidden SSID name.