Avaya Definity restarting on its own. What can be the cause?

[LouisNgan]

I'm working on an Avaya Definity system and the system has restarted on its own several times. What are some causes that would make this happen? Here are two of the logs:

#1:

Cause Action Escalated Mode Time

Interchange 4 (RELOAD) no Standby 11:45
Internal Request 1 (WARM) no Standby 11:45
Internal Request 1 (WARM) no Standby 11:45
Interchange 1 (WARM) no Active 5:32
Interchange 4 (RELOAD) no Standby 10:14
Internal Request 1 (WARM) no Standby 10:14
Internal Request 1 (WARM) no Standby 10:14
Interchange 1 (WARM) no Active 12:21
Interchange 4 (RELOAD) no Standby 20:23
Internal Request 1 (WARM) no Standby 20:23
Internal Request 1 (WARM) no Standby 20:23
Interchange 1 (WARM) no Active 5:52
Interchange 4 (RELOAD) no Standby 13:52
Internal Request 1 (WARM) no Standby 13:52
Internal Request 1 (WARM) no Standby 13:52
Interchange 1 (WARM) no Active 2:28

#2:

Cause Action Escalated Mode Time

Interchange 1 (WARM) no Active 22:57
Interchange 4 (RELOAD) no Standby 22:57
Internal Request 1 (WARM) no Standby 22:58
Internal Request 1 (WARM) no Standby 22:58
Interchange 1 (WARM) no Active 0:17