Defective (0KB) DLL in Vista dll-cache and install-location:NapiNSP.dll

Hi,

after a crash last year (while installing updates) the file
NapiNSP.dll in C:\Windows\System32\
and its cached copy in C:\Windows\winsxs\x86_microsoft-windows-n..ider-
infrastructure_31bf3856ad364e35_6.0.6000.16386_none_a9e67ecc9245d5ec
has got 0 KB in size.

I tried all i found online or what i thought by myself could be
helpful:

- Deinstallation of Hotfixed installed that day and re-installed

- copy a working dll (got it from a friend) to the winsxs folder using
inuse.exe
(that said "ok, but you have to restart to take effect" - but nothing
happened after that

- copy working dll to system32 using inuse
(doesn work either: "c:\Windows\System32\NapiNSP.dll is protected by
WFP")

- sfc /scannow or /scanfile creates error log C:\Windows\Logs\CBS:
------------------------
Hashes for file member \SystemRoot\WinSxS\x86_microsoft-windows-
n..ider-
infrastructure_31bf3856ad364e35_6.0.6000.16386_none_a9e67ecc9245d5ec
\NapiNSP.dll do not match actual file [l:22{11}]"NapiNSP.dll"
......
PublicKey neutral in the store, hash mismatch
......
Cannot repair member file [l:22{11}]"NapiNSP.dll" of Microsoft-Windows-
Naming-Provider-Infrastructure, Version = 6.0.6000.16386, pA =
PROCESSOR_ARCHITECTURE_INTEL (0), Culture neutral, VersionScope = 1
nonSxS, PublicKeyToken = {l:8 b:31bf3856ad364e35}, Type neutral,
TypeName neutral, PublicKey neutral in the store, hash mismatch
------------------------

since the crash there's a popup error window everytime i start IE or
other programms.


Anybody an idea how to fix that file without reinstalling vista?
System: Windows Vista Ultimate

Thank you for any help

Best regards
Martin