Sometimes, in the morning, the car is completely dead and does not even respond to the wireless key. So I open the door with the key manually. Then the car "comes alive" and the alarm goes off. In this case the wireless key works and can deactivate the alarm (since the car now responds to the wireless key). Sometimes I open the car manually and it does not "come alive." In this case I open the trunk and disconnect the battery. Then I reconnect the battery and it works again. It has not happened this week, but two weeks ago the car electrical system was turning itself off during driving for a few seconds, then coming back on. The electrical connections to the battery seem to be okay.

Maybe it is the immobilizer problem??