Unavailable network drives in CGI scripts

[Sprad]

I'm having problems accessing Windows network drives by drive letter in my CGI scripts. Here's a short script that illustrates the problem:

use CGI qw/:standard/;
print header();
print `net use`;
print `dir w:`; # where W is mapped to \\computername\sharename
print `dir \\\\computername\\sharename`;

The 'net use' gives me the expected list of attached shares, with the correct drive letters, but each one is marked "Unavailable".

The 'dir w:' command gives me "The system cannot find the path specified."

The 'dir \\\\computername\\sharename' gives me the correct directory listing for that share.

If I run the same code from the command line, the drive letters behave as I want, and I get the correct directory listing for both of the 'dir' commands.

Why is it behaving differently when I run it as a CGI script, and is there any way I can get it to access those drives by letter?

Edit: This is running under IIS 5.1.