Tried all the “tools” without success. Anyone else have this issue?
Are you using DT Personal or DT Pro? Which version? If DT Pro, what happens if you drag the RTF file to the Desktop?
I’m getting suspicious of a font issue on your computer. Was your “letter o” problem cleared up if you switched to a different font for a document?
In the case of the recalcitrant RTF file, what happens if you change the document’s font, then try to Export it?