My fault again - I saw PDF somewhere in error log, and assumed it was reading PDF, I missed seeing
InputFormatPlugin: MOBI Input running
on D:\Win7\TEMP\calibre_hnvf2f\ftkzvq.mobi
@
sherpa - I am still not 100% certain I know which format you are converting from and which format you are converting to. And I'm less certain which format you would prefer to read on your iPad. I had the impression it might be PDF - but then you mentioned Marvin, which I thought was primarily an EPUB reader.
BR