Hi Mark, welcome to the forums!
There is only one bug that I am aware of relating to saved games, and that is save files created before a game update will become incompatible with the game after the update, because by the nature of the update the game files have changed, resulting in incompatibilities. So I first have to ask - is the saved game you are trying to load from a copy of the game before it performed an update?
If so, then i'm afraid there is nothing we can do about this - you'll just have to cut your losses and start again.
If not though, then this is a genuine, but previously unreported, bug. If this is the case, could you please attach the save file in question to a post so that Mike (The developer) can have a look at it and see what the cause of the problem is? The file attachment box is located underneath where you type a post. Just select the file you want then click the add the file button. A new window will then open whilst the upload completes. You *might* need to kill your popup blocker to allow the upload to commence.
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