Just referring back to what Chris said about hip pain while running, I suspect this is a result of too tight muscles and weak internal hip rotators.
I had a similar problem. After training and completeing the portland marathon last year, I started to suffer from sciatica, which if you've never had the dubious pleasure of expierencing, totally sucks. Some mornings I felt almost crippled, and a lot older than my 34 years.
I was finishing my bachelors (finally) at the time and I spent a lot of time sitting at my desk in a hard wooden chair, which agravated my situation, but I was stretching regularly, and going to see my massage therapist on a regular basis, and it wasn't getting better
My wife is a pilates devotee, and she convinced me to try it. after 4 45 minute sessions, my sciatica went away, completely, like it was never there.
Rambling I know, but my point is that a lot of running problems are the result of a weakness that you may not be aware of, especially in your hips, which on most people (even fit peolpe) are tight and weak.
Sorry if this is thread drift, I'm just a big pilates advocate, so whenever someone mentions hip pain, well there I am with another long winded personal anecdote.