weird transmission problem :(
 

yesterday i was driving slowly my 2001 4.4 X5 when suddenly it emitted a stange loud noise (from the trans???) . I turned off the engine and let it cool down.i realised that when i put my car in drive mode it does not move and start emitting that rattling noise!!( in neutral too). but the car is normal and quiet in ''reverse''. does anyone know what is the problem? thanks

ps: i have faced some trans issues such as the ''metal on metal'' sound when slowing down and putting the car in reverse mode:( (nearly 100 000 miles)