Narrowing the search for the bug…
I shut my Mac Pro down each night and restart in the AM.
In the past 3 days the corrupted rendering of fonts from the Cronos Pro family when exported form any MS Word document have been different ones each day, but within each day the same font produces a corrupted pdf rendering from any MS Word document when Word's option to Save as or Print as a pdf file is used.
Adobe Acrobat (9.4.3) did raise an error message today (but not on previous days)…
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Cannot extract the embedded font 'DACHJA+CronosPro-BoldDisplt'. Some characters many not display or print correctly. [ OK ]
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…and where I have specified Cronos Pro Bold Display only one letter is displayed and in 2 of the 4 instances that letter is not among the letters in any of the words that did not display. Yesterday this same Word file converted to a pdf without any errors and the pdf file created yesterday opens without any problems, displaying the Bold Display font correctly.
So, clearly this is not a font-specific issue but rather an issue that has to do with some service that is being used by MS Word (and other applications as indicted by other posts here) to embed the fonts in the pdf file.
Since the font caches need to be recreated when I boot up each morning (at least I assume that is how it works) perhaps the error happens when the font cache is created. That would make sense from my experience. Note that within each day the same font is affected but after a complete shutdown and restart a different font (or fonts) is affected.
What is curious is that only some fonts are affected. Perhaps the previous poster that suggested this is a buffer-overflow issue was correct, or maybe in mapping out the memory for each font to be cached the OS service is not using the correct length in the header and stepping on the tail end of one font when writing out the next one.
I'm not inclined to swap out part of an Apple update so I won't try the fix noted here …which may work perfectly. I have had problems in the past with this sort of thing working with the MS Windows OS so it is a once burned twice shy thing with me. I'd rather wait for an Apply update or restore to the previous OS version completely.