Matching proxyauth.so version to PHP Zend API version

Matching proxyauth.so version to PHP Zend API version

This is the error every time I start up php:
Unable to load dynamic library
'/usr/lib/php/extensions/no-debug-non-zts-20100525/proxyauth.so' -
dlopen(/usr/lib/php/extensions/no-debug-non-zts-20100525/proxyauth.so, 9)
I have two older versions of the proxyauth.so in no-debug-non-zts-20060613
and no-debug-non-zts-20090626, but neither is compatible with a module API
compatible with 20100525, so symlinking doesn't solve the problem.
I've Googled my best and have no idea where proxyauth comes from, and
therefore can't make a new one with the compatible API. There doesn't
appear to be an extension in the php ext directory, so I have no idea what
to do next.
Thoughts?
Thanks, Bill