I have a 2004 SL 600 (with about 17K miles on it) which starts and runs fine for about 10mins.The last couple timesI've driven it (Ihave been driving it every day for the last2 weeks, prior to that very little) I have beengetting the message "electrical consumers offline" malfunction. The radio seems to quiet down when the msg came on too. This malfunction does not seem to exist for the first 8-10 mins of driving.

 

I purchased my car this year andhad the same message onmy 03 SL500 when I tried to put the top down. It turned out to be the battery in the trunk that powers all the electronics. That battery had a low charge. After charging it everything worked fine but I found it would not hold a charge and eventually it had to be replaced.
Ken