Have you used echos to determine what drives are found with $disk?

Another thing, why check if the window exists each time through the while loop? Just check to make sure the window is open at the beginning of your alias.

Code:
alias music {
  var %ticks = $ticks, %a = 1, %b = $disk(0)
  if !$window(@Music) { .window @Music }
  while %a <= %b {



So have you verified it has found your network drives?