It was the reboot after changing to PartMgr that made it work for me.So far it in my research it seems that the key is related to filter drivers for your secondary drives. I plan to contact Acronis later today to see what they say about this key, before I make any more changes.To me this is a clear sign that the activation process is too fragile to force upon us consumers. I have wasted way too much time on it since purchasing FSX. I feel lucky that I haven't done what some others have done and what was suggested to me by Microsoft and that is re-install my OS.Bruce. I looked up in my MSDN documentation how to write a filter driver and it is perfectly valid to update that registry key and add your filter driver to it. I did a few experiments. I looked up information on what Acronis does and I saw that they just append to that key, so on my system that means PartMgr wasn't there.If I switched it back to 'snapman', then Acronis worked, but FSX would ask for me to activate again.
If I put it back to PartMgr, then FSX would startup without asking about activation, and Acronis would say that it couldn't find any hard disks (not a message I liked seeing). I uninstalled Acronis True Image and re-installed. This time when I looked at the Upperfilter key, it contained 'PartMgr snapman'. Both FSX and Acronis True Image then worked fine.So the mystery to me is, if FSX is dependent on PartMgr being there, why wasn't it there on our systems?Also in the future, if PartMgr gets removed then FSX won't startup without asking for you to activate.Bruce.