Hi Joost,
At least I have managed to get this version producing sitemaps again, using an .htaccess snippet, but there are still problems. In each of 4 sitemaps this same error appears.
-----------------------------------------------------------------------
This page contains the following errors:
error on line 20 at column 57: EntityRef: expecting ';'
Below is a rendering of the page up to the first error.
http://mediacause.org/ 2013-06-28T10:52:08+00:00 daily 0.8 http://mediacause.org/quick-twitter-guide-nonprofits/ daily 0.8
-----------------------------------------------------------------------
I am not using W3TC by the way.
Over to you boss. What's the solution?
Terence.