This seems to happen if you copy rules from an Instance of an actor and then paste it into the prototype. Not sure exactly why, and the one time it happened to me I was able to recover by not saving and going back to the last saved copy, but I would bet there are ways to repair it by fixing the XML of the project. I don't know how tedious that would be, but since GS stores all the rules in XML files it should be theoretically possible to fix. I definitely wouldn't scrap your game.
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I will PM you my username and password, upload the file in there so I can download it
http://www.filesovermiles.com/
try it
http://www.FilesOverMiles.com/7d26941142e44d9cab8c68b7f336cf32
i PM you the password