I am also getting the message "FM Core has been stopped. Please start it from the System pref. pane and then relaunch InDesign." My Mac was new a year ago, and this just recently started. (Mac OS 10.6.6) I am using Suitcase Fusion 3, and have restarted the FM core from the System Preferences panel each time I get the message, which is usually several times per week.
Question is: why does it keep stopping, and why was it fine for a year? (software is all the same)
Having the FM Core stopping by itself multiple times a week is definitely not typical. I recommend contacting our technical support team to attempt to diagnose the issue. Support is free of charge for registered users.
I had this same problem. It has to do with your font management software. If you're like me and are using Universal Type Client for font management, go to your system preferences, select "Universal Type Core," System Preferences will prompt you to close, then reopen, and you'll see a check box that says "Start Universal Type Core at Login." Make sure it's selected, then restart InDesign. Should work like a charm. That invisible little font app needs to be running in the background for InDesign to access fonts properly. When it's not running, InDesign freaks out. Any little update you, or your IT folks, run to your font software could possibly turn that check box off by default.