The first thing that you should have tried is to recompile Arch's nvidia package. See http://bbs.archlinux.org/viewtopic.php?id=44281

When the nvidia package was compiled on on machine, then installed on another, the second machine still showed the fault.

Making the package and installing it on the same machine also fails.

Try the libwfb simplification - Bug  FS#9596 

Can you tell what the nvidia driver has *done* to make it magically work? Will help with http://bbs.archlinux.org/viewtopic.php?id=43792

Also, recompile Arch's nvidia-utils package.

I have just updated another machine, and the Arch nvidia package worked properly. That means we have three machines where the Arch package failed, and two machines where it worked.

The main factor that distinguishes the two working machines from the three non-working ones is that Arch was installed on the working machines from an Arch install CD fairly recently, whereas the other machines are either based on fairly old installs, or are clones made by a system copy from an older machine.

This makes me think that the problem may be related to old nvidia-related files, e.g. libraries, not being removed as they should be. It appears that the nvidia install script looks for such things, and cleans them up.

A common problem with old installations is that we used the nvidia installer in the past, or that people themselves run it. That often results in broken nvidia drivers, X server segfaults and such.

Basically, nvidia may use leftover libraries which don't match its version. Look for /{,usr/}lib/tls directories, which usually don't exist on Arch but are often created by nvidia's installer. Also, check for all the libraries in the nvidia-utils package if there is another version of them somewhere.

Is this solved?

Seems to be OK now. The problem did appear to be stuff left over using the Nvidia installer a long time ago.