The bloody paths! I had never looked there!

OK, thank you so much for incidentally teaching me (after 4 years of
use and a lot of poor advice) how to properly set an environmental
variable in WinME!

You can't imagine the time I wasted fiddling elsewhere to get apps to
find e.g. the GTK libraries!

W.r.t. the missing partition: no, there's no reference to it there.
All paths lead to places that exist and contain the corresponding
files.

The riddle is still on.