yes, I tried doing what you suggested with izarc. same original problem.
Ok, I downloaded cygwin, check.
I ran the exact commands mentioned above. Epubcheck gives me this message message and no other errors:
Quote:
mimetype contains wrong type (application/epub+zip expected)

Things open up in calibre and Adobe DE ok. Could this be a problem with epubcheck?
Quote:
Robert Admin@kunderavista /cygdrive/i/My Documents/xml/rj3
$ zip 0 cyg2.epub mimetype
adding: mimetype (stored 0%)
Robert Admin@kunderavista /cygdrive/i/My Documents/xml/rj3
$ zip 9 r cyg2.epub METAINF OEBPS
adding: METAINF/ (stored 0%)
adding: METAINF/container.xml (deflated 30%)
adding: OEBPS/ (stored 0%)
adding: OEBPS/bk01toc.html (deflated 65%)
adding: OEBPS/content.opf (deflated 75%)
adding: OEBPS/cover.html (deflated 34%)
adding: OEBPS/er001.html (deflated 59%)
adding: OEBPS/er007.html (deflated 45%)
adding: OEBPS/er009.html (deflated 41%)
adding: OEBPS/es001.html (deflated 53%)
adding: OEBPS/first.css (deflated 6%)
adding: OEBPS/first.zip (deflated 64%)
adding: OEBPS/images/ (stored 0%)
adding: OEBPS/images/cover.jpg (deflated 0%)
adding: OEBPS/in001.html (deflated 53%)
adding: OEBPS/index.html (deflated 46%)
adding: OEBPS/mimetype (stored 0%)
adding: OEBPS/pr001.html (deflated 59%)
adding: OEBPS/pt01.html (deflated 41%)
adding: OEBPS/pt02.html (deflated 43%)
adding: OEBPS/pt03.html (deflated 43%)
adding: OEBPS/pt04.html (deflated 42%)
adding: OEBPS/pt05.html (deflated 41%)
adding: OEBPS/toc.ncx (deflated 82%)
adding: OEBPS/un001.html (deflated 43%)
Robert Admin@kunderavista /cygdrive/i/My Documents/xml/rj3

I'm reluctant to make this .epub public for inspection (it's for a client). But I might be able to create another project to replicate this problem.
I gotta say, this seems really weird.