PHP 5.5 is generally build only with VC11, see on windows.php.net
So the automatic download from http://pecl.php.net or xdebug site is also build only with VC11.
You have multiple choices:
- build xdebug yourself with VC9, instructions here: https://wiki.php.net/internals/windows/stepbystepbuild
- treat Zend that they finally build PHP5.5 with VC11, like everybody else already do
- downgrade ZendServer to PHP 5.4
//UPDATE: VC9 build are now available http://xdebug.org/download.php