I also have the same problem and it is preventing me from upgrading to the latest version of the Active Directory Integration Plug-in.
The reason for the problem is that the anonymous function is not supported in older PHP versions.
Unfortunately I cannot upgrade my PHP to the latest version. Would it be possible to rewrite the ldap_slashes() function so that the preg_replace_callback() does not use an anonymous function, so it is compatible with earlier versions of PHP. ie PHP 5.2.9
Cheers
John
