Well, I ran into my first problem a few days ago. I logged in, and the game was running "choppy". In other words, every half second, it would freeze up for a bit, then start again.
I ran the file checker and it found a problem with this file:
C:\Program Files\PlayOnline\SquareEnix\FINAL FANTASY XI\ToolsUS\polboot.exe
I went through the task of re-installing and re-updating FFXI, only to find the game was still choppy, and the file still corrupt.
I went to the folder in question, to find that "polboot.exe" wasn't even in there. There was one in:
C:\Program Files\PlayOnline\SquareEnix\FINAL FANTASY XI\polboot.exe
...but it wasn't the same as the other one.
What should I try now? Should I re-install the PlayOnline Viewer along with FFXI this time? Or is something else the problem?