I was having the same issue after re-installing on a new HDD. I went through the steps of installing new drivers, installing DX9.0c, reducing resolution in registry etc.
In the end, what solved it for me was simply setting Final Fantasy XI to 'Run as Administrator'
I'm sure you know how, but for the record:
1. Go to Start > All Programs > Playonline > Final Fantasy XI
2. Right click on 'Final Fantasy XI', and click Properties
3. On the Compatability tab, tick 'Run this program as an administrator'
Hope this works for you.
After posting that, I went back and removed the 'Run as administrator' tick to check if it then didn't work. Turns out it still works..
Possibly it needs admin rights the first time it runs to set up its references to DirectX folders, or equally possibly it was something else I did at the same time.
Steps I went through:
Installed new graphics drivers (didn't seem to make a difference)
Installed DirectX 9.0c (from here
Played with windows display settings (Primary/Secondary screen identification for what its worth)
Changed background resolution from 3840x2100 to 1920x1050. Tried to run and didnt work.
Set POL and FFXI to Run as Admin
Tried to run and did work
Changed background res back to 3840x2100 and could run fine
Removed Run as Admin on FFXI and can still run ok Edited, May 5th 2012 8:28pm by Pud Edited, May 5th 2012 8:33pm by Pud