April 28, 2012
WP Install Profiles (WPIP) requires two PHP libraries, SimpleXML and ZipArchive. Both are activated by default in most hosting environments, but there are periodic exceptions, most notably MediaTemple.
If you're using a shared hosting account, contact your hosting provider's tech support. Most providers will be happy to install the library.
If you're on dedicated hosting, or need more information, try these two links:
ZipArchive is used to extract plugin files after they are downloaded from the WordPress plugin directory.
SimpleXML is used with both the WordPress API and the WPIP API to display data about plugins and to import your online install profiles.