Well done kyle! I should have realised that [ and ] were being interpreted as link metacharacters.

There are a number of odd things about this script. I'll start with a couple of minor points, The code and comments in these lines are contradictory

$status =~ s/(\W+)/ /gs; #Eliminate all non-word characters followed b
+y space.
[download]

Actually replaces all groups of non word characters with a single space.

$soc =~ s/(\W+)/ /; #Eliminate all non-word characters followed by spa
+ce.
[download]

Replaces first group of non-word characters with a single space.

$subscriber =~ s/(\D+)/ /; #Eliminate all non-digits followed by space
+.
[download]

Replaces first group of non-digit characters with a single space.

The more egregious error is the logic is badly flawed. This nested loop

foreach (@file_row) {
    while ( $line < $#file_row + 1 ) {
        $row_data = $file_row[$line];
        # Processing goes here.
        $line++;
    }    #while
}    #foreach
[download]

should be written as

foreach $row_data ( @file_row ) {
    # Processing goes here.
}
[download]

Unless @file_row was used elsewhere I would eliminate reading the entire file and do it a line at a time like so

while ( $row_data = <IN_FL> ) {
    # Processing here
}
[download]

Actually I doubt that we were given the irreducible minimum to reproduce the problem so I think @file_row is only used here and should be eliminated.

Update: I'd also change

open(IN_FL, $input_FL) || die ("unable to open directory");
[download]

to

open IN_FL, $input_FL or die "unable to open $input_FL:$!";
[download]

You are not opening a directory and it will help debugging if you print the reason you can't open the file.