I just tried the code below and it worked. One thing to check is to be sure you're setting SSDIR to where your srcsafe.ini file is located. From the SS GUI you can click the File pulldown menu and in VSS 6.0 anyway it will show you the path to the srcsafe.ini file just above the 'Exit' command.

#!/usr/bin/perl
use warnings;
use strict;

my $sspath= 'C:\Program Files (x86)\Microsoft Visual Studio\VSS\win32'
+;

$ENV{SSDIR}="\\\\server\\path-to-ini"; #or local path

#my $cmd = "\"$sspath\\ss.exe\" Dir ";        # listed files in defaul
+t project
my $cmd = "\"$sspath\\ss.exe\" Dir \"\$/\"";  # listed subproject fold
+ers
print "\n********************\n\$cmd=$cmd\n";

system $cmd;
[download]

Update: Although you might be providing the path to an ini file already, since you have installed a new version you might have multiple srcsafe.ini files. By checking the path in the GUI you can verify you are using the correct one.