I couldn't save new documents this morning, and after trying several routine attempts, I noticed the folder in the "Save As" dialog box was "bullets". I customized a bullet list in my first document that failed to save as, and in doing so, the normal "Save To" folder was changed automatically to the "bullets" folder. After changing the folder back to "documents" in the dialog box, I was able to save again. If you're going crazy, wondering why your document won't save, this might be one reason - check the "save to" folder in the dialog box to make sure it's not a write-protected folder.