Windows 7 randomly Locks active user out

OS: Windows 7
CPU: Intel i5-2410m
Mem: 4 GB

When using Windows 7, it randomly goes to the lock screen during an active session. This has been the case on multiple computers running Windows 7. Immediateness proceeding the lockout the screen flashes black and than shows the login screen.

All of the external hardware is the same, one computer was a desktop, one is a laptop.

I'm not sure what would cause it, but that is the same behavior I would expect on a server when someone connects to it by RDP.

I'm on a Protected home network, and there is RPD is disabled. I do have a web filter installed that passes all network traffic through a remote server. Would something like that cause this issue?