You know, this seems to be a little familiar to a problem I had with downloading a patch from Oracle. The problem was on AIX but I got some similar-sounding errors.
Turns out that the documentation that "shipped" with the patch was wrong in terms of the cpio flags. It said use "cpio -idmv". However, the latest documentation on TechNet said use "cpio -idcv".
I've no idea if this will solve your problem, but it is something to try.