Tranny going bad?

95 E20 runs great.  At the stop light yesterday, wouldn't move when light turned green. Revs fine but not moving. Turned the car off and on a few times and everthing was back to normal. Shifts all gears fine.  Talked to a mechanic and he is saying that it sounds like my tranny is gone.  Anyone had this problem?

Sorry Bud. He's Right!

similar happened to me about a year ago in my '99 300TD - I just topped up the auto box with the recommend fluid and its been  fine ever since.  Interesting that the auto box is meant to be sealed for life , however I just broke the seal in the engine compartmemt and filled it up 0.5 litre at a time until the prob vanished (it took 1.5 litres)- be careful not to overfill as  that will l damage the box.