http://www.kood.org/terminal-server-patch/
- Download the termserv.zip file below and extract it somewhere. (You have to be registered to see the file)
 - Reboot into Safe Mode. This is necessary to remove Windows File Protection.
 - Copy the termserv.dll in the zip to %windir%\System32 and %windir%\ServicePackFiles\i386. If the second folder doesn’t exist, don’t copy it there. Delete termserv.dll from the dllcache folder: %windir%\system32\dllcache
 - Merge the contents of Concurrent Sessions SP2.reg file into the registry.
 - Make sure Fast User Switching is turned on. Go Control Panel -> User Accounts -> Change the way users log on or off and turn on Fast User Switching.
 - Open up the Group Policy Editor: Start Menu > Run > ‘gpedit.msc’. Navigate to Computer Configuration > Administrative Templates > Windows Components > Terminal Services. Enable ‘Limit Number of Connections’ and set the number of connections to 3 (or more). This enables you to have more than one person remotely logged on.
 - Now reboot back into normal Windows and try out whether Concurrent Sessions in Remote Desktop works. It should!