The only time I experienced this was when I changed the eqgame.exe and/or eqmain.dll (can't remember which one) just for experiment purposes, but when I tried to log in it couldn't find the eqhost.txt file because it was in a different format.
i.e. This is from a client that works with 6.0:
Code:
[LoginServer]
Host=eqemulator.net:5994
and this one worked with a really old client:
Code:
newlogin1.eqemulator.net
5994
So maybe the the .txt file your using somehow doesn't match the format that EverQuest is looking for. I hope this was at all helpful...