This article discusses an obsolete extension, "FireWire Lynx Enabler".

If you purchased a non-Apple FireWire PCI card, the accompanying software may have installed an extension named "FireWire Lynx Enabler". If you are using FireWire 2.3 or later, you should move this file to the Trash and restart. FireWire 2.3 includes better support for these FireWire PCI cards.

To check the FireWire software version, open the Extensions folder (inside the System Folder) and select either the FireWire Enabler or FireWire Support file. Then choose Get Info from the File menu. The version of either of these files is the FireWire software version.