If what you say is true, you have a very broken Perl. 
>md dir

>copy nul file
        1 file(s) copied.

>perl -le"if (-d $ARGV[0]) { print 'dir' } else { print 'not' }" dir
dir

>perl -le"if (-d $ARGV[0]) { print 'dir' } else { print 'not' }" file
not

[download]

I could see the opposite (always getting the else part) due to being in a different working directory than you think you are, having trailing whitespace in your file name or attempting to use wide file names.

Update: Oops, I read it backwards. You are getting the else part.

In reply to Re: Directory checking on Windows XP by ikegami
in thread Directory checking on Windows XP by ack

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