i found a solution thanks Sephiroth as it is done by NTSwitch. i really dont know why this doesnt work when it is as windows server 2003.
what i dont like is, i feel microsoft is just modifying their windows code a little, disable and enable some stuff and sell it as a new product for sky rocketing prices.
just check the system properties below. it says
Windows XP Professional Version 2003!
the connection does not terminate any more, even after a user log off and another user logs in, provided that the connection is avaiable for everyone.
all what i want now is fast-user switching. 
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