[help needed a.s.a.p.!] PHP XML file acting very strange

The hosting provider of one of my clients has had an update recently [unfortunately, I don’t know exactly what], and now my SQL/PHP-built XML file is acting up.
One moment the content is there, the next it’s not… It only happens with the content that in the XML has a CDATA tag. The script has been working without a problem for the last 3 years… Haven’t heard from the client for the same amount of time.

As the client has a big meeting tomorrow, in which she needs her website, I’m in a slight hurry/panic here [22.15 in Holland at the moment].
Any quick ideas? Anyone? Please?

[edit] So it’s not just de XML files, but a simple PHP echo in another file as well… Title: no prob, text: gone and the back again.

I have never encountered anything like this before…