This is a bad error message:
$ miniunzip hmw50.zip
MiniUnz 1.01b, demo of zLib + Unz package written by Gilles Vollant
more info at http://www.winimage.com/zLibDll/unzip.html
Cannot open hmw50.zip or hmw50.zip.zip
The file is there, it is just truncated.
$ ls
hmw50.zip
$ unzip hmw50.zip
Archive: hmw50.zip
End-of-central-directory signature not found. Either this file is not
a zipfile, or it constitutes one disk of a multi-part archive. In the
latter case the central directory and zipfile comment will be found on
the last disk(s) of this archive.
unzip: cannot find zipfile directory in one of hmw50.zip or
hmw50.zip.zip, and cannot find hmw50.zip.ZIP, period.