I've experienced being booted for being idle for too long when I was only idle for a few minutes (like, five). I double-checked the settings and it's set to a full 30 minutes, much longer than it seems like I waited.
This issue is now being reported by the users. They're not chatting anymore, and this auto-logoff thing while someone "holds the room" is killing the chat feature.
http://forum.equisearch.com/forums/p/37964/274373.aspx#274373
Using the Nov 12 build.