Hmm, it seems that some ROMs don't load from the zipped versions. For example, the R-Type 1/2 Taisang Versions simply won't load from the zipped version, but they work if they are unzipped.
I managed to get all the above ROMs working correctly - except Cyber Core (U) - by extracting then rezipping them, even though there was nothing wrong with the original zips as far as WinZip was conc ...
I noticed that the games Raiden (U) and Cyber Core (U) had severe graphics errors, yet Raiden (J) [o1] and Cyber Core (J) work fine! Is this a compatibility issue, or are the 'good' dumps bad?