do you think it could be the installer that's creating the directory?

try uninstalling limewire (not sure if mac's have a way of uninstalling programs), deleting the .limewire folder from your preferences, and then reinstalling. see if afterwards a limewire.props directory is made, instead of a limewire.props file.

or if it does make the file, try restarting and seeing if it's somehow converted to a folder.

or if nothing even is made there, try starting limewire the first time and keep an eye on the .limewire folder, seeing what's added to it -- a folder or a file.

etc...