Word 2007 does not appear to have that problem up to at least 100,000 characters. But there are some other side effects:

1. It took the macro 50 seconds to re-color all 100,000 characters.
2. The file grew from 22KB to 818KB.
3. It takes Word a very long time (up to 20-30 minutes) to complete the tallies for the status bar (lines, paragraphs, pages, sections, characters). The same document with all of the characters set to "automatic" (black) completes the tallies in seconds. Curiously, if I load the all-black document, wait for the tallies to complete, then run the macro, the tallies appear to start over from scratch even though no characters were added or deleted.
4. The little Word Count pop-up formats the totals wrong if they exceed 5 digits (see attached image). 100,000 is displayed as "100,00".

sigh

Attached Images

Word 20130105 Word count number formatting error.jpg (59.3 KB, 31 views)