My X3 2.0d from 05 also has problems with start.

Symptom: Key on ignition everything works, all lights on, audio ok, windows ok, mirrors ok but car wont start and no crank.

Last Wednesday evening after car parking it refuse to start again.

On Thursday morning again wont start and I have to push it and it starts.

Went to work and park the car, start the car two or tree times and everything is ok.

On Thursday evening wont start again, leaving the car parking and went back home with a friend.

Friday morning I was planning to put the car on dealer, but guess what, car starts without problem all day, and at night when went shopping, car refuse to start again, push it again and it starts.

Tomorrow I'm planning to leave it at BMW Dealer. But I believe they will not find nothing wrong.

Tks.