Sorry to hear this , but I just joined the activation gang. Been using fsx since it came out added delux with in weeks. To date never an issue until 6 hours ago when for absolutely no reason fsx starts calling for key activation. Put it in , nope won't verify (I'm On win 10 and have been since it was launched with never an issue) now, had to use phone activation, get my code it says verification successful but multiplayer option on the left menu disappeared which red flagged me as that's a sign something I'd screwed. Following 16 attempts at putting in the code provided on the phone system I get fsx to fire up once and then when I restart fsx back to square one , so the successful activation isn't. Read everything, went through the ResEdit checked the "PartMgr" was right. Rebooted , nope nothing now working including repairing, dropping the firewall, turning off the virus protection for many of the verification processes. Now I'm in to backing up all my scenery files, simobects, gauges and anything else I can backup. I've even backed up the backup........ and of course Microsoft is as useful as a chocolate fire guard. So, it look like a theme going on here
W10 will work as long as the internet is on. Once the internet is off then it asks for the registration key. I had to use the phone system and that worked. Also i had to change a value in the registry which is explained on some forums.
So not sure why you have other issues with W10.
Well today 24 hours after the issue I decided t make a last ditch attempt to register the game again, bearing in mind its sudden demand to be registered again two years after its initial registration and continued use. This was attempt number 17. I fired it up, across came the registration screen as it had done previously and then I put in the original FSX base pack key , it dialed home as expected but instead of crashing back to the demand to use the phone system the servers responded and it.................................Registered!.
Now, call me suspicious etc but, strange that I did this process today when the US was in effect still asleep and comms traffic hitting the US servers was slightly lower. From looking on the MS sites and community there were many of the same issue surrounding MS game gift cards not registering, Xboxes unable to communicate, games firing up and refusing to communicate with the MS servers. Checked with a friend my side who works in retail and she confirmed that yesterday there were complaints galore about game gift card and games and machines not registering which in turn caused retailers to fight off the angry and disappointed customers citing their Christmas ruined because their products didnt work, and today - they work! I smell overworked servers failing to cope with the traffic demand. This runs alongside Adobe running out their Product Authenticity Protocol software which is aimed at cracked Photoshop to the greater degree and which is causing some pretty nasty responses as it collides with genuine registered software causing it to report every 15 minutes that its in fact illegal. Of course some are indeed, many are, but the genuine ones are really not happy.
Back to the FSX. After 12 hours of head banging and googling I noted one issue that FSX kicks up. If you change computer hardware configurations, i.e. new motherboard , introduction of Ram or graphic cards etc it can frequently cause FSX (the order boxed dvd version) to fight back and want to "phone home" - why, because these version had validation scripts in there. And guess who just added an extra 4GB to his rig????
I did find this strange because when people complained about FSX not working with Windows 10 , I wasn't seeing it, mine has always worked.
Its nothing to do with it - The online failed multiple times which I now strongly suspect was the Microsoft system in meltdown - The phone system worked but every time I then closed FSX and restarted I had to go right through the whole process again. on 27th Dec I tired quite early in the morning and the online cleared it immediately. Ive today spoke again to a friend in retail and yesterday they had customers in multiples complaining that their MS products wont register - certainly seems like the Christmas present registration system with TU on Microsoft. If my memory is right this happened about 4 years ago as well over the Christmas period when almost the same issue were being reported. Ive tested my setup here and its all ok no even required to reinstall. The give away that something just isn't working MS end is when you have the phone registration and when you put it in the multiplayer option on the left of the main start screen is not there.
That is odd because i had to use the phone system and it works every time. Its the online that causes 2 issues for me. W10 works until internet is off. W7 will not work no matter what. So i use phone for both.