If you reprogram the pic with the firmware, then setup the SSC with starting channel, grouping and so forth with the SSC utility, the checksum of the program of the pic will be different and it will fail a verify against a 'blank' firmware. That doesn't mean that the PIC firmware is bad (but that doesn't guarantee it is good either). If the failure happens kind of in the middle of the verification process, not right right away, and the SSC had been set with a start channel different than 1, less nodes than 128, or/and any other options that are not the default ones, there is a good chance that this is what you are seeing.