Had a similar problem, except my interior lights would flicker somewhat and dim gradually. It was worn brushes in my alternator. Cheap and a 5 minute installation for new ones. Works perfectly now. I'd test to see if your alternator is charging properly. There's plenty of info on how to do so in the archives here. Good luck!
2007 E550 4Matic - 61,000 Km - Iridium Silver, black leather, Sport package, Premium 2 package
2007 GL450 4Matic - 62,000 Km - Obsidian Black Metallic, black leather, all options
1998 E430 - sold
1989 300E - 333,000 Km - sold
1977 280E - sold
1971 250 - retired
"And a frign hat. They gave me a hat at the annual benefits meeting. I said. how does this benefit me. I dont have anything from the company.. So they gave me a hat." - TheDon