POL Will Launch But Not If FFXI Is Installed?

Hello friends, I have a weird problem.

I wanted to load up FFXI for some good ol' nostalgia after being off for three years or so. I am running Win7 64-bit.

POL will open as normal before I install the main game, but after I install the game, it won't open at all. No errors, no crashes. Just doesn't open.

I have repeatedly uninstalled and installed. I have tested by uninstalling the main game, leaving the expansions and opening POL (It opens but obviously I can't play the game).

I have also kept POL open while installing the main game, was able to update the game and get into the game, but after I shut it down, I wasn't able to open it again.

Help! :(