One problem related to ignition switch has been reported for the 2001 Mercedes Benz ML320. The most recently reported issues are listed below.
My 2001 mercedes Ml320 SUV developed a defect in the ignition switch, whereby the key came out while the car was not in the park position. In June 2009, the car was parked in my driveway and ignition turned off. I didn't realize that the key came out when the car was in neutral instead of park. After a while the car rolled backwards and hit a neighbors car and the garage door opposite my driveway. I reported the incident to mercedes and the dealer said that the defect cannot be covered free by the manufacturer as the car was out of warranty. I paid almost $1000 to get the ignition switch defect fixed.