can you tell what proc library version (libproc-version-no.so) is being used? you can find the library file at /lib/liproc-version-no.so location.
If it is libproc-3.2.8.so, the issue could be with this library. Replacing to older version (3.2.7) might help. To revert to older version do the following steps.
1. Go to http://procps.sourceforge.net/download.html
2. Download procps-3.2.7.tar.gz
3. extract the package - tar zxvf procps-3.2.7.tar.gz
4. cd procps-3.2.7
6. copy proc/libproc-3.2.7.so to /lib/
7. copy w (binary file) to /user/bin (keep the original till you test it okei)
Now, run w and see if this gets you the correct users. If so, do make install so that working binaries and libraries is installed in your machine.