Yep, the injectors was the problem in my case but try to rule out the fuel pressure as these guys suggested although why you would have the right pressure when is cold vs. warm.
Can you find the exact pattern start vs. no start?
If you try to start the car within the next few minutes after it was stopped, will it still start?
I believe for mine it was around 20-30 minutes to flood the cylinders. The car would start almost with no issues during the first 20 min or so.
http://www.xoutpost.com/bmw-sav-foru...njector-4.html
The same discussion here:
http://www.xoutpost.com/bmw-sav-foru...d-weather.html