A client of mine just replaced their one pc at home. Their old XP box got very old and slow so they purchased a new Win 7 home box.
The Win 2008 server at work allows me to connect remotely by rdp with no problem and no changes were made so the user shouldn't have a server or acount related problem.
The Win 7 came with AVG free. I thought it might be blocking port 3389 or any remote connection rule. I uninstalled it to eliminate the possibility.
The new PC can ping the server, but cannot connect by RDP. I remoted into their new pc and verified they are using correct credentials (domain\username).