Cannot find php_sqlsrv extension - 5.3, threadsafe
===

I've followed the answer to this question to the letter:

http://stackoverflow.com/questions/5425322/connection-between-mssql-and-php-5-3-5-on-iis-is-not-working

I'm using XAMPP with threadsafe 5.3. I've copied the files to the extension directory (while leaving them in the /php folder) and I've added the extension lines:

    extension=php_sqlsrv_53_ts.dll
    extension=php_pdo_sqlsrv_53_ts.dll

When I do this, Apache fails to start, giving me errors in `eventvwr` like:

    Application popup: Warning : PHP Startup: Unable to load dynamic library 'C:\xampp\php\ext\php_sqlsrv_53_ts.dll' - The specified module could not be found.

Except, obviously, that that file DOES exist in that spot, and php.ini is pointed at that extension directory.

What's the problem?
