Part of our earlier two posts on Remote Desktop Connection: SSH Tunnel through Putty and DD-WRT for RDP / RDC and Enabling RDP on Windows 7 Home Premium Edition where we setup our RDP connections, we came across an issue of automatic disconnects in our RDP sessions.  Tricky to debug, here are the steps we took to solve this problem.

Frist we fired up WireShark and used the following filter string on the target IP (Right click then View Image if it appears too small):

ip.src==192.168.0.23/24 and ip.dst==192.168.0.15/24

Whcih shows a checksum problem.  And your event viewer shows this:

And this:

And checking on the network card properties, we see this:

Then we simply disable the above, press OK then let the system reconnect the network card.  Hope this works for you too!

If this doesn't work, there are two microsoft knowledge base articles that can be references for further information on a possible RDP update that might have impacted things.

http://support.microsoft.com/kb/2621440/en-us
http://blogs.technet.com/b/nettracer/archive/2013/01/18/rdp-connections-might-fail-due-to-a-problem-with-kb2621440-ms12-020.aspx

Searching for this in Control Panel is a bit tricky but sorting the list yields a list one can scroll through.  And if that doesn't work, there is always the TightVNC or TinyVNC option that I've used as well. 

Cheers,
TK