Originally Posted by
Deimos
Let me guess, you're using a Radeon 9200 video card?
A lot of people (including me) seem to be having this problem. I'm not sure why, but I seem to have about a 50% chance of being able to log on, where the other half of the time it just restarts my computer. You can look at different forums and lots of people are posting what fixed the problem for them, so I have no idea what's actually causing it.
The "solutions" I've seen so far have ranged from downloading the newest drivers, to resetting all the options in FFXI Config to default, to waiting 20 seconds once you're on the title screen until you see a big tree, then choosing Select Character...