I am using CGI as you assumed. Sorry, I should have been more clear on that. The script does work on the Mac, althought I haven't tested it with IE4. It has successfully worked with MacOSX (Camino, IE, iCab, Safari), it also works fine on Linux (mozilla) and in Windows (Netscape). However, it is not working in Windows IE (XP/6.0) -- I'm trying to test on other Win/IE combos. So, it appears to be an IE issue.

It does print the filename, but not the content (there's a 0K file), and the error log doesn't show anything.

Also, this problem exists on two different servers:
Apache/1.3.26 (Unix) PHP/4.2.3 mod_perl/1.27 on FreeBSD
Perl 5.005_03

Apache/1.3.27 (Unix) mod_ssl/2.8.11 OpenSSL/0.9.6b FrontPage/5.0.2.2510 PHP/4.3.0 mod_throttle/3.1.2 on Linux
Perl 5.006