Is there a reason you are specifying the full path to "explorer.exe" ? Normally, it would always be available in your PATH, so you can simply
exec "explorer.exe .", and it will be found and executed.
The following works just as expected on my Windows XP machine:
perl -e " exec qq(explorer.exe F:\\)"
perl -e " exec qq(explorer.exe .)"
The first opens Explorer pointing to the F: drive (at the root), the second opens the current directory.
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