I work in prepress using a Mac running OS 10.6.8. Frequent loading and unloading of fonts using font management software is required with only a minimum number of fonts kept in the system font folder.
Soon after a hard or soft boot fonts don't display correctly in Iron. Square boxes with incorrect characters appear instead of the correct characters. Are there required fonts Iron needs installed? If it's a matter of a corrupt font cache it happens so frequently that rebooting is not a good solution.