I apologize if I missed your post and e-mail 3 weeks ago, but in all fairness you could have posted a follow-up before now. I had just come home with my newborn daughter at that time and had a lot of catching up to do. Also, sometimes we handle issues like this in the chat room and then the forum post doesn't get updated with the solution...
Anyway...
C:/Program Files (x86)/everquest/eqgame.exe (Tue Jun 08 23:45:25 2010)
This is not a current version of EverQuest.1a.
We don't provide support for use of private servers, and our software is not guaranteed to work with old versions of games. There's also EQMac, which this version is not; EQMac is too old of an EQ version to be used with ISBoxer. Either way, if you really want it to work for this version, a quick google for your issue turns up a recommendation from 2006 to delete eqclient.ini in order to solve this issue, after which the problem was solved for that user.
http://www.lavishsoft.com/forum/viewtopic.php?p=11700 -- From memory I believe it actually has to do with the game's windowed mode setting.
1b. If you're NOT using a private server, then the problem is most likely just that you have ISBoxer launching an old version of EverQuest instead of your current EverQuest install. Note that current EQ installs no longer default to the Program Files folder, but instead to
C:\Users\Public\Sony Online Entertainment\Installed Games\EverQuest. You can use Add Game from the Inner Space menu to add it if necessary, and then point your ISBoxer Characters at the updated Game and Game Profile. You can also delete the old EQ folder...