ntdll.dll doesn't allow it to start.

[mrpeters]

Hi, I got a problem where the ntdll.dll doesn't let the game start.
I played the game untill 10 pm, after that I had to go to bed cause I had a 3 hour test in school the next day. After I got home I switched on the computer and tried to start the game... It didn't work. I have now been trying to fix the error for around 5 hours. No success, I have used Uniblue 2009 (all of them), tried changing the ntdll.dll with the same version and all that (I checked the file version and everything with it, the only exception was the size which could make a great deal but it still was for Windows XP home edition).
I really don't want to format my HDD because I got over 550 GB of my games and files on the computer that I really don't want to loose.
Please help me.
The game ran perfectly before this error. No mods or anything.
I have tried to use a backup point but it didn't work.
I have updated Windows fully, still didn't work.
I know that I should not try to do anything with the ntdll.dll but I had no other choice then to at least try to fix it.

Please help me, this is one of the best games I haven't finished
Have played better though but I haven't finished this one yet ^^