There isn't a download of 6.28 on Calibre site. I have the zip files that I kept when I first downloaded. Email me your postal address and I will gladly send you a copy on disk - I'm sure Kovid will not mind that as he offers this as freeware/shareware. It would be useful if Kovid posted an older versions download facility on his site so that others could use them when they meet these sort of problems. My email is
dennis@dldoyle.freeserve.co.uk
regards
dennis