This sounds like a Simplink problem. There's potentially an issue with the signal coming from the TV causing the soundbar to think it's on. I understand that you'd typically want this feature on but if the soundbar is randomly turning on, a temporary measure would be to turn the AutoPower feature off like tonysix00 said. In the meantime, I would recommend checking firmware updates and contacting the manufactur of both the TV and the soundbar. Since OP mentioned it didn't happen on the previous TV I'm pretty sure the offender here is the TV.