Plugins wont activate (PHP Errors)

I just tried activating my plugins on the admin panel and when I do I get two PHP errors instead. This is what I get:

Warning: require_once(ultimate-tag-warrior-actions.php) [function.require-once]: failed to open stream: No such file or directory in /home/public_html/art/wp-content/plugins/UltimateTagWarrior/ultimate-tag-warrior-core.php on line 9

Fatal error: require_once() [function.require]: Failed opening required ‘ultimate-tag-warrior-actions.php’ (include_path=’.:/usr/lib/php:/usr/local/lib/php:.’) in /home/public_html/art/wp-content/plugins/UltimateTagWarrior/ultimate-tag-warrior-core.php on line 9

Is it my version of PHP? Shouldn’t be since everything else in WP works just fine.