My E46 did this but I am not sure it would apply here but worth a try as it doesn't cost any money and takes 5 minutes of your time.
Try pulling all the fuses related to the radio and then reinstall them, on my E46 there are 2. This will reboot the modules and solved my problem. You might also check the relay and everything is in the back fuse compartment.
Fuse box BMW X5 E53