I tried opening one of my own (very important, lengthy) Word docs today, only to get this message upon opening:
This document cannot be edited because it contains a read-only embedded font.
And when I tried typing something it said:
This modification is not allowed because the document is locked.
This is a very lengthy, terribly important document, so I definitely need to solve this problem. Any suggestions? :help:
You might try Ctrl-A and then Ctrl-C to copy it and then paste it into a blank document.
That’s so simple it’s, er, time for more coffee! 
Thanks, it worked! 
track down your font and kill it by font substitution… or iot will happen again.
i used to find large docs (100,000 words and up) would crash all the time, especially once you start building tables of contents and hyperlinked indexes into it, so I kept many backups, in more or less stripped down versions, and they would occassionally save the day when the master got corrupted. Office for Mac 2004 seems to have ironed out at least some of those bugs, but i still regularly crash documents with many edits in them with track changes enabled. Oh, and disable fast saves… that means saves are a bit slower, but more stable when you reopen them later.
and “copy all, open new, paste” was a great workaround too.
Not sure what that means. How do I figure out which font it is, and do you mean I can’t use that font anymore, or do I just replace it with itself?
I’m not using track changes.
I didn’t have it enabled – I checked.