Just to update this post ...

Edward contacted me directly and I advised him that I've seen that message when using the newer Adagio installs and/or installing on newer OSes when using mapped or substituted drives. I advised him to use the UNC equivalent for the install path and all was well.

The mapped drives still run the apps fine but have issues with the Adagio Installs on some machines and giving misleading messages like the one above. Why I have no idea but as soon as I have an issue with the mapped/substituted drive during an install, I just use the UNC path and so far so good. That is, of course, assuming that the network/folder rights are actually OK ... but especially in the case of upgrading where the site has been happily using (which also requires write access) Adagio then in most cases the rights would not have suddenly changed when you go to upgrade - not sure why the screen shot seemed to suggest that files in the folder were read-only.

Regards, Pete