I know flock often doesn't work on Win(9[58]|ME) boxes. Not sure about NT. Try running this:

#!perl

open(TEST, '>', 'file.tmp') or die "Can't open file: $!\n";
flock(TEST, LOCK_EX) or die "Can't lock file: $!\n";

print "Passed\n";
print TEST "Hello, World!\n";

close(TEST);
[download]

And see if you get any error messages.

----
I wanted to explore how Perl's closures can be manipulated, and ended up creating an object system by accident.
-- Schemer

Note: All code is untested, unless otherwise stated