Make sure you've removed ALL the dlls from the old PHP distribution, including php5ts.dll (people tend to put it in some weird places and forget to upgrade it after that).

I have verified that the script interpreter and ALL .dll have been updated (I only run one copy of the script interpreter in the php root for this type of reason specifically).

What's the exact error message?

Well I've figured this out.  While it wasn't the PHP distro's fault technically, the problem is vary precarious.

I use an openSSL binary package (available at: http://www.slproweb.com/products/Win32OpenSSL.html).

The current version of the openSSL bin package (0.9.8) puts its own copy of libeay32.dll & ssleay32.dll in a 'path' accessible folder (e.g. /system32/).  openSSL 0.9.8 is using .DLL version 0.9.8.5 and if that folder occurs in the PATH variable before your PHP folder (or wherever your PHP .DLL's are) then the environment will load the first copy of the .DLL's it encounters; in this case it was loading the .DLL's from the openSSL package before the PHP .DLL's; which do vary in version.

PHP 5.2.1 is using ssleay32.dll & libeay32.dll version 0.9.8.4 and the current openSSL package 0.9.8 uses ssleay32.dll & libeay32.dll version 0.9.8.5

The openSSL .dll's were stepping on the PHP .dll's, once I removed the openSLL .DLL's everything worked; except that I can't use openSSL now.

I don't know what the difference is between the two .DLL versions are but I do know it kills PHP LDAP ability and prevents PHP from loading into Apache as a module.

Not PHP problem -> bogus.