set_markup() UTF-8 encoding problems

["John Hobbs" <john velvetcache org>]

Hello,

I have an app that opens a text file with content marked up with
Pango, then puts that text in a label with set_markup.

My problem is that sometime it errors out with:
Gtk-WARNING **: Failed to set text from markup due to error parsing
markup: Error on line 11 char 2: Invalid UTF-8 encoded text - not
valid '[markup text here]'.

The weird thing is it isn't consistent. The same thing tried a few
times in a row will yield mostly successful, with an error every 5 or
so tries, though the interval is not consistent either.

Anyone have any ideas?

- John