In this try I made sure $I is an integer and not a string. So it now looks like this:
code:
$server = "server"
$shares = "Mark","www","hdd","Public"
$drives = "e:","f:","g:","h:"
$I = "0"
$I = val("$I")

FOR EACH $mapping IN $shares
use $drives[$I] \\$server\$mapping
$I = $I + 1
NEXT

And guess what? It still won't work...

Mark