We've had close to 100 calls about users logging into our AIX server. The users open up about 3 to 5 sessions in the server. After 2hrs of idle time, users are frozen or stuck in the IBM UniVerse Application. We (system administrators) have been blaming the application (which we'll take to our SA Graves!!!!), I just want to verify that it is not the system. I have heard that AIX has a 2hour idle time session before it either kicks you out or freezes the users. Has anyone had experience with users getting booted from an AIX session or frozen? Any advice would be greatly appreciated. Thanks.
I'm not sure why you posted this AIX question in Solaris section, maybe a mistake ? 
Anyways, I've had this problem before, well, sort of, but I'm not sure whether will help you.
I've been establishing many remote sessions to a servers located outside of our office in VPN environment. After a while, I got disconnected 
. I finally found out that it's a firewall issue. To describe my situation, I will use this quote from the net :
So I added "ServerAliveInterval 60" into /etc/ssh/ssh_config file, which means that my machine will send keep-alive requests every 60 seconds, thus keeping the connection online.
Once again, I'm not sure if this could be related with your case, but you have to make sure that you've checked firewall configs, and any network related service. Also, did the users noticed being disconnected after exactly 2 hours, or approximately ? This should be clear, because if this is firewall or another network rule, it will be stated somewhere in exact digits, e.g. 3600 secs. Otherwise, if the drops vary at their times, something else is the issue.
HTH.
If that is a terminal, then check if TMOUT variable is set or no. It can also be a cause.
But most probably it is a firewall or a networking device that is disconnecting your sessions. Most of my previous experiences were a firewall.
Regards,
KapilRaj