Thanks to all for the various suggestions. Will give them a try. I did try the MS repair facility but it was beyond it's capabilities. BTW my allusion to 6 hours of phone calls was due to the fact that my system is running a ssd 250gb and a 1tb hdd. The msfs had been loaded onto the ssd for speed etc. but due to the size of the sim I ended up with 9gb left and an upgrade to install that would have overrun that. So being a bit nieve I thought perhaps I can get all the fs stuff transferred from the ssd (drive C) to the hdd (drive D) so I contacted ms and was patched through to Cairo. The guy I spoke to said it would be tricky but could be done and he started off at 5.30 our time. After almost 2 hours and having given him control of my pc he said job done. Sure enough it seemed ok. But next day I tried it and I couldn't get the fs to work at all. However he had given me a job number and said to quote that and I would be put through straight to him. I tried that and ended up speaking to a young lady in Nigeria. We went through the whole procedure again (2 hours of it) and she said it's ok now, and it was, it worked like a dream. Fs here I come. Guess what, next day back to square one. To cut a long story short I got back to ms then Nigeria again (different lady) and we did another 2 hours torture. Anyway, since then it has worked but only if I start windows, then without doing anything else I restart windows it works. But if I try to start msfs without doing a restart first it's no go. Hope I haven't bored you too much with my tale of woe but it makes you wonder how these things work.