What I'm doing is having my PC wired to my laptop via an ethernet cable, and the laptop wirelessly connected to the internet. As I mentioned in my first post, I am doing this because my PC inexplicably doesn't like using wireless: It'll keep dropping packets so every so often I'll get a second or two of everything freezing. This does not occur when I have ICS set up. So, yes, I have a router, but with my PC wirelessly connected to it FFXIV is damn near unplayable.

As for the suggestion about port forwarding, the problem is I can no longer set up ICS in the first place! I get the error message this thread is named after when I attempt to turn it on.

So, hey, alternate question: Any idea why a PC would routinely drop packets over wireless, when a laptop in the same area does not? The result is the same over three different wireless USB NICs tried in various USB slots, as well as a wireless NIC card slotted into the motherboard.