VNC Disconnect Issues
I am running CentOS 6.3 on a quad core with 8GB of RAM.
I am fairly new to linux but have managed to get the system working as file server and backups.
If I connect to VNC through a VPN I can stay connected as long as I want. If I connect from a pc on the local network, it will let me in and I start to do something and after 30 seconds I am disconnected. I looked at the logs and they were saying timeout exactly 30 seconds after the connection completed.
It looks to me like the connection is not being acknowledged as having completed, so is disconnecting.
I'm not sure what is causing your VNC timeouts (unless something is sending Xvnc the IdleTimeout parameter at some point), but perhaps you can try tunneling VNC over SSH. That may solve your timeout issues, and also has the bonus of providing a secure connection (no passwords, etc. are passed in the clear).