It could be that the popping or cracking noises you hear are caused by different parts inside the TV expanding as they warm up. It's caused by the thermal expansion the metal chassis of the TV goes through during the warm-up phase. These sounds are normal, and happen in a variety of different environments.
However, the volume of the sound suggests a possible component problem. If you'd like to get it checked out, here's the thread where you can get details on arranging for service technician to check it out: http://forums.cnet.com/7723-13973_102-542437/service-issues-click-here-for-help/
Please help. I have a 2006 model. Stated making humming, buzzing noise now after 30 min. Or so it makes loud popping, crackling static noise like its gonna blow up!! I'm wondering do I fix it or just junk Another Samsung? Any help very appreciated.