Did you delete the folder? Also, sometimes, what you can do is, you can create a NEW eqhost.txt file (just put the regular info into it [see code]) and then just place a copy of it into your EQ Folder. It might be some kind of bug.
Also make sure you have administrative access, and make sure (if you are using Windows Vista/7) that UAC (User Account Control) is turned off.
Code:
[LoginServer]
Host=login.eqemulator.net:5999
Host=eqemulator.net:5999