DS7400Xi system is arming itself at random times, history shows user 97 is arming.
Arming by user 97 indicates the system was Auto-Armed. The DS7400Xi Version 3+ can be programmed to auto arm thru Master Programming Mode. Enter Master Programming Mode by entering the Master Code and # 0. Select 1 for Auto Arm setup programming, enter the area number and press # to go thru each day to determine if Auto Arming has been programmed. Disable Auto-Arming by entering  + [#] for the arming time.
Notes - On the DS7400 Ver3+ panels, if programming is done from a Master Keypad that is not in single partition mode, the user will be prompted to enter the partition they wish to program. If the user has access to more than partition, all partitions where they have authority will be programmed. If programming from a standard keypad, or from a Master Keypad in single partition mode, only the partition that the keypad resides in will be programmed.