Your code works for me, after I made a simple substitution of opendir(TEXTFILES, ".") || die "Couldn't open the text file directory: $!"; instead of trying to open directory "desktop".. You need to change to the "desktop" directory, because you're doing the test on the current directory..
HTH

The full code that worked for me follows:

use Cwd;
print "Current dir is: ", cwd, "\n";

local $_;
opendir(TEXTFILES, "c:\\CA_LIC") || die "Couldn't open the text file d
+irectory: $!";

@data=readdir(TEXTFILES);
foreach (@data) {
print $_, "\n" if(-d "C:\\CA_LIC\\$_ ");
}
closedir(TEXTFILES);
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Update:ZZamboni types faster than I do :o), obviously, he's said what I've tried to say too, better, in fact :o)