This works on another Mac under OSX 10.6.
The log file when I try to typeset the .tex-file mentioned in the first sentence below is very brief:
The argument "/Users/robertblackstone/Dropbox/C-tests/Initials/Initials-test1.tex" is not a valid TEXROOT path.
(There is no file "/Users/robertblackstone/Dropbox/C-tests/Initials/Initials-test1.tex/texmf/tex/plain/base/plain.tex")
...ne/context-minimal-04-11/tex/texmf-osx-64/bin/mtxrun:10769: cannot open /Users/robertblackstone/texmf/tex/symb-uni-zapf/: Permission denied
I have no idea what the folder symb-uni-zapf does in my texmf/tex directory. Should I perhaps thrash it? (I cannot change its permissions.)
And there is indeed no file: "/Users/robertblackstone/Dropbox/C-tests/Initials/Initials-Test-1.tex/texmf/tex/plain/base/plain.tex" but why should there be one?
Thanks also to Wolfgang Schuster and H. vd Meer for their quick replies that, though not offering an immediate solution, reassured me that I will eventually be able to use mkiv on this Mac.
Regards,
Robert Blackstone