Glad you found us. You probably do not need to worry about this. If you rely on passing the file objects rather than the file names, then the problem goes away. For example:
get-childitem myfiles* | copy-item -dest c:\other|path
If you really do need to work with the filenames in the way you describe, then do something like this:
copy-item -path "$filename" -dest $path
Does that help?