@Cego
That probably because when mounting virual drive dosbox add "/" at end. So if you mount just a directory somewhere, like "work:test", then for dosbox it will be "work:test/" which is ok for amigaoses, but when you mount pure drive it then add "/" at end and we have "work:/" , which is not ok for amigaoses.

That mean that some simple ifdef should be added in dosbox's code where mounting of virualdrives placed.