Hello….weird problem but hoping someone can help!

Server: PowerEdge 2850 – 8 core – 12gb ram – 32 bit processor
OS: Redhat ES 6
Setting: University setting .. use server for Computer Science student accounts (350 users)

Every so often the system just boots you, no matter what you are doing. Has happened to me as well when editing a file or just sitting at the command prompt.

Most users use putty to connect, though I have used SSH Secure Shell as well, get booted with both.

Things I have checked or done:

Changed out ethernet cables, changed out the ethernet card. Fiddled with the number of user processes, number of system logins etc.

Have looked at settings in sshd.config relating to Timeouts.
Have connected machine to a different physical switch.
Have increased user limits.

Anyone have any ideas what might cause the system to just boot users randomly like this?
Source: The UNIX and Linux Forums