Hi Lemur,
When I tried this, it is showing below message:
C:\Windows\System32>EXPAND.EXE nvlddmkm.sy_ nvlddmkm.sys
Microsoft (R) File Expansion Utility Version 6.0.6000.16386
Copyright (c) Microsoft Corporation. All rights reserved.
Expanding nvlddmkm.sy_ to nvlddmkm.sys.
Can't open output file: nvlddmkm.sys.

Did I do anything wrong.

And also when I checked timestamps for both nvlddmkm.sy_ in Video folder, and nvlddmkm.sys in system32\drivers folder --both are having same date: 26\04\2007

Joshna

Originally Posted by lemur

This solution comes with a money back guarantee (pay the man, Ken)...

During the installation of the most current Vista drivers, an OLD file
nvlddmkm.sys is copied into windows/system32/drivers and not the current one
in the install.

Fix: Go to windows/system32/drivers and rename nvlddmkm.sys to
nvlddmkm.sys.old. Go to the nvidia directory and find the file nvlddmkm.sy_
and copy it to windows/system32. Using the cmd window (DOS box) type
EXPAND.EXE nvlddmkm.sy_ nvlddmkm.sys. When the expansion is complete, copy
the new nvlddmkm.sys to windows/system32/drivers and restart the computer.

Your computer should now work properly.

You will notice that any uninstall and reinstall of nvidia drivers will not
remove the old nvlddmkm.sys file and will not overwrite it with the newer
version. You have to do it manually. I do not know why this happens but who
cares as long it is fixed.

It sounds like your drive may be bad - if you tested in on two computers and the installation failed. I'm sorry if you stated this before. Who is the manufacturer of the drive?

Do you know who the manufacturer of your hard drive is?