Cache Issue for XVD C6455

We are seeing some form of cache error with the C6455. This occurs in 4 

boards out of about 150 boards so far.

The error appear as a bit error in either L1 or L2 cache after initial 

power up.  But will go away if a reset is applied again after some code 

executiion without power cycle.

We have checked the power up and reset sequence, which complies with the 

datasheet requirement (3.3V first, then 1.2V and 1.8V together).

Delaying the reset deassertion after power is stable does not seem to 

make a difference.

We would like to check with you to see if TI has seen similar problem 

before and if you have any suggestion.  Note that on the same board 

(same power supply and reset), there are total of 2 DM648 and 2 C6455.  

We only see this issue on one of the C6455, and the problem are not at 

the same PCB location.