Some of these headaches are entirely preventable.
Here are some great tips for avoiding health care hell, courtesy of Bankrate.com, which also has solid consumer info on other aspects of health insurance:
Know what your policy covers. It sounds simple, but read and review it regularly -- particularly the parts about exclusions and limitations and how to appeal.
Talk to your health care provider about what's covered -- and what's not.
Take the policy seriously. If it says you need prior authorization, don't go for care without getting the official OK first. It's a huge pain to fight for these things after the fact.
Keep detailed notes about EVERYTHING -- when you received the authorization and from whom, the date of treatment, what you discussed with your doctor, what follow-up is required, etc. Note every phone call, every rep you speak with and every relevant name, date and place. That way, if you need to fight a decision through the appeals process, you'll be armed and ready.
Save copies of all your paperwork from the doctor and the insurance company.
Make sure claims are filed immediately, and if there is a delay in payment, call your insurer right away.