I've found the problem and fortunately only two strings were
affected. The large number of untranslated strings in the Czech
version of the book were due to an unrelated problem with my local
Zanata configuration. I've fixed it and all translated strings have
been restored to the Czech version except for the two affecting all
books. The files and strings are:
Download_Fedora.po : "The image file for the Fedora 17 live CD is
available from
http://download.fedoraproject.org/pub/fedora/linux/releases/17/Live/i686/Fedora-17-i686-Live-Desktop.iso.
Download and save this file to your computer."
Boot_your_computer_from_the_CD.po : "Either press
Enter to select the
Start Fedora 17 option,
or wait for the countdown to expire. "
The version number of Fedora was causing the problem in each case.
I'm unsure why, because the po files were outdated even though I've
refreshed them since I last worked on these strings myself in en-US.
So - and I do apologise - I will have to ask those who were working
on the Czech, Dutch, Italian, and Ukrainian guides to revisit these
po files and translate these two strings again. I have uploaded the
refreshed pot files, so the po files are now awaiting completion in
all locales.