i had the same issue with my e 53 4.4... it used to be notice when u drive for 30 min or..i guess when oil get warm... too bad... the all of a sudden... the car wouldnt drive and there was excessive slippery in the tranny.. and the emergency progam was engaged.. i took it to the dealer.. and he said... u need to get ur transmission fixed...
i wonder how such a transmission failure would happen in one day. .without previous notices. unless they consider this disturb in downship .. a start to complete tranny failure... my car is still at dealer.. i took the tranny for ZF dealer to refurbich.... headach..
so guys.. be careful.. i believe changing oil.. is a recomended...
good luck