Electrical help? Radio/Steering wheel controls

[x5glenn]

My Radio and Steering wheel controls sometimes take a few seconds to several minutes to become functional after my x5 is started. Radio will be blank and sw controls will be completely dead (lights and all) and then after a short period of time they both come on. What could be causing this? I have had this problem for a few months and yesterday installed a new battery replacing my 6 y.o. original one. Problem still occurs. also i have noticed that when the radio and steering wheel controls are off the airbag light and also the seatbelt warning lights stay on and they disappear when radio and steering wheel controls come on. extended warranty expired 2 motnhs ago so i would like to try to narrow it down before going into the dealer and letting them hike up the bill.

thanks