Hi Mike,
Unfortunately, I have not seen anything like this. Not on Mactel, PPC or PC. One question though ... Are you using the internal Archicad PDF writer or Acrobat Pro to generate the PDFs. I like the Arcrobat output much better. There's an idea ... if you are using Acrobat Pro, did something happen to that application. It might not be your Archicad at all.
See you in San Antonio???