[tex-live] [win32] bibtex and makeindex - Forbidden to open for writing

[Karl Berry]

    D:\mydocs\tmp\document.1.blg: Forbidden to open for writing
    I couldn't open file name `D:\mydocs\tmp\document.1.blg'

>From http://tug.org/texlive/doc/texlive-en/texlive-en.html#news:

  ... BibTeX and Makeindex now refuse to write their output files to an
  arbitrary directory (like TeX itself), by default. This is so they can
  now be enabled for use by the restricted \write18. To change this, the
  TEXMFOUTPUT environment variable can be set, or the openout_any setting
  changed.

I'm glad Siep knew another incantation that may help you.