[XeTeX] Re: o/ or O/ goes to ? or ? (oslash or Oslash)

[Mike Leonard]

I get the same problem with the letter L. As in "Pall/Mall". The L by 
the slash comes out with a little slash through it. I don't know the 
name of this character. Since I write most of documents as plain text 
(in Textile format) and then convert to LaTeX, I'm hoping for a 
solution that doesn't involve manually fixing every instance of the 
offending characters (\hboxes seem to help). And is perhaps more 
elegant than a search-and-replace over the entire text. Any 
suggestions?

Thanks,

Mike