OK, two problems.
First, my comment in
Issue #529 was incorrect. The file does not need to be an exact multiple of 512 bytes. The core problem (in v3.5.0) was that the size of the file did not match the size specified in the header of the file. This was corrected in v3.5.1 by making the size of the file 42 records (5,376 bytes).
@Robb, I suspect you somehow have a disk image with the v3.5 version of zpmldr.sys on it. The erroneous file size is 41 records, which is what you reported. I have confirmed that both zpmldr.sys and cpmldr.sys are 42 records long in v3.5.1.
Thanks, Wayne