Opticum locking up

Hi All.
My X7 HD is locking up recently since I upgraded my broadband service to 50Mhz. If I view a FTA channel for about 20 minutes or so and return to a channel which needs an internet connection the box will lock up and require a reboot. I am running cam 2.0.11. I have installed an 9600 prima at the same location and it runs fine. The problem only occurred when I upgraded to 50Mhz. If I stay on a premium channel all will be ok.
Any help or suggestions.
Thanks in advance.