I am having a similar problem under windows 7.
Rardarbox will run for a couple of hours at most but the the software will say that the box is not connected when it is plugged in. I check the device manager and radarbox is still connected to the computer, but the program is not seeing it.
I have checked that I am running the latest drivers, it is very annoying as I did not have this problem with my old computer running vista.
Any Ideas wopuld be much appreciated.