Recurring Error-3001 when I zone

Over the past month or so, a few zones I try to enter result in getting stuck at the "downloading data" screen, and eventually time out into an Error-3001. I try to log back onto the same character immediately, and again it won't pass the black "downloading data" screen. I log on another character, and they are fine, unless I try to zone into the same exact area as the first character.

It started out with Yahse Hunting Grounds. A friend who also plays had to log onto my character to move him out of the zone, before I could successfully log on him. Then several days later, it happened again in Port Windurst. Then eventually Qufim Island. And just today, it happened in Buburimu Peninsula.

I worry that whatever is happening, it will affect more and more areas, until I can barely play at all. I have tried "Check Files" multiple times, and nothing is corrupted, neither with my PlayOnline Viewer nor my Final Fantasy XI data.

I don't know what to do anymore, besides reinstalling completely. But if none of my files are corrupt, would a reinstall even help at all?