When you save a project, extra information is saved to permit loading the project with a later version or on a different platform. This error has the following cause and solution:
Load the file using the Visual Basic version in which it was previously saved, or on the platform in which it was previously saved, and then save it again. If you don't receive any error messages during that save, you should be able to load it in the current version or on the current platform.
For additional information, select the item in question and press F1.