99 times out of 100 it is what noob/protected said. Delete chat window ini.
This happens alot when you do things like change your screen size, copy mq2 folder between computers....
MQ2ChatWnd.ini stores the location of your MQ2 window.
Also make sure that mq2chatwnd is still being loaded when you start up. If you open macroquest.ini with a word processor (notepad) you should see this in your [Plugins}:
mq2chatwnd=mq2chatwnd
If you do not see that then type
/plugin mq2chatwnd once in game or add it to .ini file.