Sometimes when printing PDFs on my Windows XP with an HP photosmart 2410 printer the text becomes gibberish. It's kind of hard to describe, so I've scanned in an affected page below:
(not very good scan quality, I don't think my scanner was quite working right and the page was faded to begin with)
EDIT: Here is the original: http://www.nlcbsa.org/files/d/usr/16/Medora%20Itinerary%202012.pdf
There is no consistency in when it happens.
EDIT: It seems to only happen when printing multiple copies. Sometimes it will start out like that, other times it will switch halfway through, and more often nothing happens.
EDIT #2: Figured out what the "gibberish" is. The binary code for each changed character is exactly one more than the code for the proper character (i.e.
0x20 (space) becomes
0x21 (exclamation point) ). Now to figure out why that happens...
(using Adobe Reader X)