John and Gary,
I understand that this might be frustrating, especially some of the answers. However my colleagues are correct. Your HOA is a governing body of your community, some are run by the home owners, some are run by companies. However the rules can and do change by votes, etc. You need to check the most recent release of the documents. If you are in violation and do not make a change, the HOA can fine you, and they could in fact create legal problems. Do they often do this, probably not, but they could and HOA's really should not be messed with unless absolutely necessary. In Virginia, when you bought the home, a rider/addendum was attached to your deed for a PUD - planned unit development. If there are issues with the HOA and they file a lien, this could affect a sale in the future.
I have to say, that does sound a bit ridiculous that they would have you change the door color that it is original to the community. My advice: check your governing docs and if you have an issue, go to your next HOA meeting and politely make an objection.