I realise that this means a corrupt flight plan but every flight plan that I make in fsx turns out to be corrupt. It reminds me on start up every time and tells me that 'the flight plan will not be used'.Any ideas why fsx would produce corrupt FP's?Thanks

I get that too. How can I fix? Just delete all my flight plans?

I cannot believe that Microsoft couldn't even get something as basic as this right. You have to delete the corrupt file and then file it again, it is a pain. I have reverted to the GPS now.May have to reinstall fsbuild again.