We have the same problem with our Samsung tv monitor
Our three year old tv takes from 20 minutes to an hour to turn on. Sounds like the same problems everyone else describes. We have learned to turn it on when we get home from work, go out and do our exercising, shopping, etc, and come back and watch the news that we have DVR'd. We leave it on mute the entire time we are awake and at home. Pretty sad state of affairs and there is no way we are taking it apart and fixing it ourselves. We will just buy a new large screen monitor and make sure it is NOT Samsung!