Starter won't crank

Sporadically, my 96 E320 won't crank. The warning lights light and everything else seems fine but no starter. I took it to the dealer and they "deleted numerous codes" which resulted in the car starting fine for three days but this morning again -- no crank. I finally got it started by trying at 15 minute intervals and cycling the key numerous times. After I got it started, the odometer/trip odometer and the digital read out for temperature and clock were of different intensities (the temp and clock readouts were substantially brighter). Its at the dealer again. Any thoughts?