there's a small bug in your code, Sifmole:

($choice <= scalar(@user_files))

# should be
($choice < scalar(@user_files))
[download]

as you are now asking for the number of array elements after you unshifted the blank element, e.g.

  0     1     2
blank file1 file2
[download]

and scalar(@user_files) = 3 but $user_files[3] is undefined!

-- Hofmator