Vista - ntdll.dll

Ok, here it is.
OS is Vista Enterprise
The problem happens with several applications, mostly with word 2007. every log says the fault is ntdll.dll
The file is present in C:\windows\system32\
Any effort to change the fila with a new one tells me I have no rights (with both local admin account and enterprise domain admin account).
Trying to register ntdll.dll results with error message that dll or ocx file is missing or corrupt.
sfc /scannow in cmd gives no files with errors.

Any idea how to solve this?

to replace the ntdll.dll sure if you have a bartPE, a linux, ubuntu or any other OS dvd, you can boot from that dvd make your way to c:\windows\system32 delete the file and replace it with a known copy. Dont know if that will cure the problem but when you boot into windows it should register the new file if it is the correct version

Hope this helps, and let us know if it doesn't

Ken

@zigzag3143: haven't tried your solution so I don't know if it helps or not. But the thing that helps is sfc /scannow. the problem disappeared imidiately.
Anyway, thanks for your assistance