Gibberish when printing PDFs
Solution 1:
Have you tried Print as Image (Print dialog -> Advanced)? If the problem still occurred, it would indicate that it was on the PC side not the printer side. If it did not occur it would prove nothing, but at least you would have a workaround.
Solution 2:
Could you try installing the lastest drivers for your printer and update your PDF reader? It seems either your PDF reader or the printer driver did not process the fonts in the PDF correctly. You may want to try another PDF reader and see if it prints correctly.
If none of these work, you can try converting your PDF to vector graphics and print that instead. Printer cannot do font substituon on graphics, so it should just print what you see on the screen. The easiest way to achieve this is to install a free PDF printer software like PDF Creator and print your PDF to that.
If the file generated by the PDF printer is already gibberish, then it's definitely your PDF reader's fault.