From time to time, my system, when I try to login TRHOUGH or AFTER a remote connection, locks up the login session. I can't login anymore, the screen turns black (the monitor is still active, the image is black). Especially in the recent case, the system did not come back from the lock-up, and I had to reset the computer. Any idea what might be the issue here?

More information: Both Computers are Windows 7, The RDP Server has a wired connection, the Client has either Wireless or Wired. The network card involved on the server is a "Realtek RTL8168C(P)/8111C(P) Family PCI-E Gigabit Ethernet NIC (NDIS 6.20)" card built-in on an ASRock Mainboard. I'm using either local LAN or internet connection through NAT/Router.