First, lets start with that, this tutorial wont work if your computer is connected to Windows domain. If you are not sure whether you are connected or not, following the next steps will not change anything fatally.
Anyway, if you want to be able to use several parallel sessions of Remote Desktop, you must have at least basic knowledge of Windows OS, in particular with Windows registry. If you do not have any experience with the adjustment of the registry, it is better to use the help of someone more experienced, or did not go further, even that if you just follow the next steps you will be able to enable concurrent remote desktop without log off other users.
The first thing that you have to do is to create one file with name add-to-registry.reg and put the next lines inside before save it:
Then just double click on the file and accept including to the registry.
When you are ready, you have to reboot the system in Safe Mode. But before that you must have a specific Windows DLL file called termsrv.dll with version “2055″ coming with Windows XP Service Pack 1.
Then go to Safe Mode and copy it to C:\WINDOWS\system32 and C:\WINDOWS\ServicePackFiles\i386 and reboot the PC.
When you are back to Normal Windows load check the option Use the welcome screen located in Control Panel – User Accounts – Change the way users log on and off as in the following screenshoot:
If you are ready with the change, the next step is to edit the registry.
There go to : MY COMPUTER\ HKEY_LOCAL_MACHINE\ SOFTWARE\ MICROSOFT\ WINDOWS NT\ CURRENTVERSION\ WINLOGON\ find ALLOWMULTIPLE TSSESSIONS right click on it, choose “Modify” and then in the “Value data” field set 1.
With the last step we finished with the changes that must be done, and now you need only to restart your Windows in order to allow the concurrent remote desktop connections without logging off other users.
Related to this tutorial is one called: Change Remote Desktop Port Number which is about how to change the default RDP number and make your computer more secure.