If you're busy perl-scripting on a windows machine, and you're getting unexpected behavior from the command-line utilities your shelling out to (say, 'find', or something), it may be because instead of getting the utility you think you're getting (/usr/bin/find, for example, from cygwin) you're getting something totally different (dos find, for example)
This can lead to a lot of confusion when you try to figure out why you aren't getting consistent results between systems you're working on.
Solution? Use full paths. If you want the cygwin find, say "/usr/bin/find" or you just can't be sure.