Figured I'd just make a new post since I've seen several individual posts all about the same problem. If you try to log in but eq crashes after character select, go into your eq folder and delete the file: UI_<CharacterName>_<ServerName>.ini Obviously you replace the < > with your specific info. Then when you log back in, do not close the tab labeled combat. You can remap combat to another window or tab, but you must leave the tab there. For some reason closing that tab corrupts your UI ini file rendering you unable to log in. You can reload your custom ui, make new chat windows, eat cheese with orcs, as long as you dont close the combat tab.
