We are running FM version 7.2b144 on MS Win xp Pro (32 bit), and I did not notice this until service pack 3 was installed. I believe I have found a work around to the situation and another contributing cause. If graphic files are placed directly in an anchored frame instead of importing by reference, the file somehow becomes misplaced. If you right click the graphic and open the Object Properties dialog box, and see the phrase "no referenced file" below Main Editor: Referenced File: in the lower left hand corner, this has happened. I found if I removed all graphics files without references and imported them by reference, the source file may then be properly saved. I am also using a program called CCleaner, which removes cookies, temp files, browsing history and the like from a system. If the program settings are chosen too aggressively, and the application runs when FM has a file open, this same error will occur, even if all files are referenced properly. I don't know if SP3 has some similar application which is now running in the background and causing this.
To summarize, if you want to retain SP3, I have eliminated this error by confirming the links to referenced graphics files and avoiding using 3rd party "cleaners" while FM is open.