Folks,
I can across a message that I have not seen before in Project 2010 and wanted to pass the resolution and error window to assist any others that may be in the same dilemma. It is rather an easy fix – to clean up your cache.
Enjoy,
Jacques

Error Window:

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Went to Project Options (File –> Options) and used the Clean Up Cache button to select all those projects in my cache and Remove From Cache.

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Then retried the save and it worked.   Have you seen any other errors – let us know.