I am seeing infrequent corruption of the Flash memory on an 16F877A device.
I first suspected my "bootloader" routine (which actually doesn't program on
boot-up), but I can't find a reason why it would jump into the bootcode at
just the right point to corrupt the memory, bypassing the normal checks on
the data to be programmed (comparing length and checksum). I have brown-out
detect enabled and it is triggering at very close to the nominal 4.0 V. Any
ideas what, besides a code bug, could corrupt the program memory?

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