Okay, found a solution to the problem (finally!)
In Acme type
And right-click it. The default partition names are on line 15:
for i in C D { # add more drive letters to suit
replace "C D" with the partition names. On my laptop, the partition names are C, F, G and H. So line 15 becomes:
for i in C F G H { # add more drive letters to suit
That solved the problem!