Don't know if this helps but late last year I visited a new location (in a part of the world I don't normally frequent) and had similar messages from PPM.

It turned out that my hosts had installed some kind of malconfigured proxying firewall which automagically inserted JavaScript blocking code into any HTML it saw. Unfortunately it couldn't tell XML from HTML and hence all communication with PPM was hosed.

The messages I got were something like what you are seeing. I was only there for a short time, so I never needed to fix it, once I had got home a clean connection allowed me to grab what I needed.

I proved that the rewrites were happening by tracking the PPM modules and then explictly grabing the XML file. YMMV