Clearing the fog

Last night I watched Donnie Darko for the first time. It wasn't what I expected at all. I enjoyed it - a lot - though I hadn't the foggiest idea what the film was about. Was the rabbit a figment of his imagination or a person? Did he really travel through time or was it all a dream? What was the point of Drew Barrymore's character?

I reacted this same way to one other film - 2001: A Space Odyssey. I've seen this movie so many times and always come away feeling like there's a towel over my head. The cinematography is fantastic, the score is wonderful, but I still have no idea what it's about. Who is the baby at the end of the film?

Does anyone want to shed some light on my confusion? Do any of you have any theories or ideas about the meaning of these films? Am I being dense?