This sounds immediately to me like you're behind a proxy and it's the thing actually sending you this message. However it is, PPM seems to be trying to communicate with its server using a HTTP method that isn't permitted, which is strange -or- your proxy is transforming somehow the request into one that confuses the PPM server, which seems probably more likely, especially if its communicating over what looks like HTTP, but what is actually a PPM-specific protocol.

Make sure you've gone through these instructions, but from your comment above, it seems like you may already have.

Otherwise, ActiveState's remedy, unfortunately, goes like this.

NOTE: If none of the changes in this document work for you, you may download individual packages from here ActivePerl 801 and later or here ActivePerl 613 and later or here ActivePerl 522 and earlier and install them according to the directions in the README file contained within the ZIP file. If you want, you can also keep a local repository, with several .ppd files in a permanent repository directory, and their .tar.gz files in an x86 directory beneath that.

Hope this helps - good luck,
  -Adam

P.S. nmake lives here, should you need it.

Update: Also - for kicks, search on google for a ppd file for a module you'd like to install - try something simple first, something like this: ppm install http://ppm.gingerall.cz/RDF-Core.ppd - I'm curious to see what this results in... I can't say whether ppm uses HTTP to search its own database, but it would seemingly have to do so to pull this ppd file.