I have 43" Toshiba Theaterview

It sounds like your system is overheating. That can cause the power supply overload to shut the system off.
Try adding an external fan to increase the airflow, especially over the main electronics section. Make sure that you don't blow heat from the bulb back into the system. If this works, there are fan bars that you can purchase that are less obtrusive.

You need a new bulb