Lsass exe system error invalid parameter passed to function

This is a panic story, i donot found a categor for 2003 server thats y im seeking help here.
In my laptop i've windows server 2003Enterprise on c:\ drive and windows xp on g:\ drive.
on a bad day morning a tried to start server, i provided pwd to the user 'Administrator'
the first window i saw is like this " Windows saving your settings..." and then
immediatly a window like " windows is logging of ...." " shutting down....". System started booting process again.
tthis is happening contineously. even safe mode also d'nt workedout.

then i booted from windows server 2003 CD. and Repaired my server which is on c:\ drive.
it workedout, my server started without prompting pwd, after logging in no service, no application was started. here i set my administrator pwd to *****.

and later i started server frm cd/dvd and went into repair mode,
there i used to repair some file in windows\system32\config\.....
after that i restarted my server, now it is showing an error "lsass.exe system error"
and the message is " an invalid parameter passes to service or function"
i tried to boot from cd, went to repair mode . it is asking a pwd, when i entered the pwd
which is recently set , system saying that is invalid password.

please do help me some one,
i've very important applications installed on my laptop, there is no problem with XP.
all struggles are with Server.
this is very urgent.

Thanks in Advance