Try disconnecting the antenna at the Radar Box side, also the USB cable, then reconnect a few times. Make sure the antenna cable is not putting any strain on the Radar Box SMA connector. If you just physically touch the outside of the antenna jack at the box with your hand, does it make any difference?
I don't know if it's static or a bad connection in the box but my box was been doing this since I got it a few weeks back - I could go over and just barely adjust the antenna connection on the box and suddenly it lights up with 150 messages from only 15 or 0.
It's not my coax or the BNC>SMA adapter - I've changed connectors, etc and everything tests perfectly.
I noticed several times when I touched the connector the box completely stop receiving until I let go.
I was using a pre-amp antenna and though it has ESD built in, the problem was worse then. Since using just the little RB antenna on my roof the problem has not occurred again. Odd.