Could you tell me the difference of using the internal clock and external clock (32.768Mhz).
"In noisy environments, noise can couple to the external crystal pins, and PLL may quickly lose lock. A PLL interrupt is provided in the interrupt controller. The core clock is immediately halted, and this interrupt is only serviced when the lock is restored.
In case of crystal loss, use the watchdog timer. During initialization, a test on the RSTSTA can determine if the reset came from the watchdog timer"
Is there anything other than the above.