The Quartus® II software version 5.1 SP1 issues this verification error after programming the flash device through the PFL if: 1. The flash data bus width is chosen as 8 bit, and 2. The most significant bit (MSB) of the flash address bus is 1 The Quartus II software version 5.1 SP1 incorrectly computes the number of bits needed to address the flash device, causing the flash device to be incorrectly addressed.
This problem has been fixed beginning with the Quartus II software version 6.0.
For Quartus II software version 5.1 SP1, contact Altera® Applications for the patch 1.01 to fix this issue.