A couple of customers have reported that after flashing their E38 pcm with a newer or older operating system have corrupted their pcm's NVRAM. From the best we can gather GM made at least two different E38 pcm's and when you try to flash in an incompatible operating system it will lock you out similar to tunerlocking.
Because this is not an HPTuners related issue we will not offer replacement credits or pcm.
Our recommendation is to simply not try and mix & match operating systems into these pcm's as doing so is simply too costly.
Easy way to tell if this is the issue is to grab an infolog while connected to the vehicle, if the vcm id number looks garbled the nvram is corrupt as shown in the attachment
Thanks,
Bill