That's crazy. I just experienced almost the same thing last night.
I switched the source on my W205 to my Ipod, and a song began playing like normal. Then, I tried to skip to the next song, and the head unit responded (beep and pulse touch), but the Ipod didn't change. It just kept on playing the same song. Then, I tried going back, pausing, etc. Nothing was working. About that time a message popped up on my head unit "Error 011". I opened my glove box and grabbed my Ipod. I unplugged it and plugged it back in. No change. I turned it off and back on. No change. The error message actually went away, but I still couldn't flip through songs or pause it or anything. I turned off my head unit, then my truck, then turned my truck back on, reset my head unit, then turned it back on. It's been working fine ever since. Go figure.