Blackfin Bootup Issue?

We have been building products with the Blackfin ADSP-BF537 (and earlier products with the ADSP-BF533).  We boot from external flash, use primarily the Eval Board core as the schematic with the ADM708 reset IC and have two Linear Technology LTM8023 modules that convert the DC input voltage (typically 10-28VDC) to 3.3V and 1.3V for the core.  Sometimes we get a report that when power is turned on to the unit it does boot up and recycling power remedies this.  The problem is VERY infrequent.  For example, in one application where there are 80 units in the field it may happen one time in a week and on a different unit each time.

Our units are typically used as on-board audio players in amusement park mobile vehicles.  On one application where the problem occurred more prevalently, we found that customer's power supply was crowbarring at startup creating an very undesirable input voltage waveform at startup.  Changing to a more robust supply fixed the issue however, on this an other instance we still see the infrequent problem.

Does anyone have any similar experience with this type of issue and have any solutions to offer?