"Remove Key" Message on Mercedes
 

A friend of mine has a Mercedes (CLK 320) that won't start
intermittently... the message on the dash reads, "Remove Key" once
removed and reinserted, it sometimes will start, sometimes not. There
are no check engine lights or codes. Any ideas on this one? I'm
thinking it might be the key itself maybe? is this a dealer only fix?
Thanks in advance~
Lucky S.