My 2009 CLS 550's radio keeps shutting off and tries to reboot every 5-10 min. Just the Mercedes display pops up and the radio will play with all functions not available. I

I had the exact same problem with my 2009 SL550 a few months ago. Fortunately for me, it happened during the delivery process and the dealer had included a MB CPO warranty with the car. The dealer tried rebooting, software updates, etc and never could get it fixed. They finally replaced it for free with a new unit. IF your unit is not under any warranty - consider an after-market Nav, Radio, Bluetooth, etc unit. They have far more functionality that MB's stock unit. Expect to pay about $2,500 plus labor to replace your unit with an MB unit. Dash kits are available that will make your replacement unit look exactly like it was stock. Kenwood and Pioneer are each good considerations. IF your car has the fiber optic system (like the SL has) do not worry, the after market unit will wire right in with adapters.