First, verify that the pump for the indirect is getting power. If it is, and the pipe to the indirect is not hot, if it isn't an air lock, the pump is bad (or you've got a valve closed that shouldn't be). My guess is that the boiler is timing out, sensing that the water temp is high, the return is not cooling it off, and shutting down because it doesn't make sense. After a reset period, it tries again.
Another thing to check is that the thermocouple for the indirect is fully seated in the well in the tank. But, since the water is not the proper temp, and it does call for the boiler to heat, it probably is okay. There are test procedures for the sensor, but you probably don't need to run them. They generally require a multimeter.