I have a 2001 Mercedes E430. I'm having problems getting it to start. Usually, I have to get a boost to get it to start. But I just discovered that disconnecting the battery completely gets it to start as well. After disconnecting the battery it will run fine for a few days. Also, I hear a single click sometimes when it doesn't start.
Also, may be related, my windows usually have problems going up. They will go up a little then stop. And I have to repeatedly push the up button. I noticed after disconnecting the battery this time, I did not have that problem.