It seems you have a startup script that runs when you open your file. If you have Advanced open the script debugger before opening your file and diagnose from there.
And check the "health" of your hard drive and computer's account permission settings. FileMaker automatically creates a temp file when it opens a database file. If it can't create that temp file, you will get this error message. Issues with user account privileges or your hard drive's formatting might be the cause of such an error.