Followed that instruction prior to my re-install attempt and got nowhere.
Managed to get somewhere as there was a post mentioning that entries get made under the product code too. Managed to find these and delete with prejudice and got round to be able to re-install.......which was where some more fun started.
Install base pack, all great. Started up, flew a flight, shut computer down and rebooted. Installed Acceleration, started up, flew a flight, shut down FSX, FSX had fatal error and restarted. Close FSX, shut down computer, reboot and then FSX fails to start with Fatal Error every time.
Remove Acceleration and all work fine...except for a big fat OOM when loading up FlyTampa Dubai after only being in game for 5 mins.
Decide to then just add SP1 and SP2 and all goes well until SP2 which brings back the Fatal Error message.
See some more posting about certain dll's which can cause this. Delete them but still no joy.
My next step to get back into the air is remove all that I have added onto the dedicated SSD, reformat that completely and then do some research and set up a dual boot on that SSD with W7. Seems to be my next logical step as W8 is refusing to play ball with it.
All my driver files are up to date also
Fingers crossed I can get to the bottom of this and get myself back in the air soon