UPDATE.
I hate loose ends, so I post here my findings for anyone interested.
Games are now loading and played properly.
The culprit was eXoDOS 5 with some of the files from eXoDOS 6 that both use as a frontend the LaunchBox app. Apparently you CAN'T upgrade from 5 to 6 (like I tried unsuccessfully) using "same name" files from both editions. After having tried EVERYTHING (software and hardware wise), I ended up deleting my eXoDOS folder and install the version 5 of which I had a full copy (unfortunately, full version 6 torrent file is inactive with no seeds or peers).
THANK YOU for your time reading this tread.
