It turns off randomly for like 2 minutes, and turns back on, sleep mode is off. What's THE PROBLEM?

What model Insignia is it? The later models come with a two year warranty. Insignia covers in-home support on most models too. Call 1-888-BESTBUY (1-888-237-8289). It's hard to say exactly what is wrong with the TV without seeing the TV itself. You may also be able to go directly to the store where they can assist you. Keep in mind that Insignia is Best Buy's brand, and therefore Best Buy supports it (within the warranty).