2002 Nissan Xterra Doors unlocking automatically

Could be your keyless entry remote. Mine locks my doors all the time as if I was pressing the button. Changed the battery in the remote and give it a tap every now and then when it is acting up. Very annoying when your sitting in the drive way and your horn is beeping and lights flashing as if your locking the truck when the keys are on the table in the house. I will tap the remote on the table a few times and it will stop. I need a new remote but refuse to pay $70 to get one.