Exact same problem:

Warning: require_once(/home/twodice1/twodiceboxing.com/administrator/components/com_finder/helpers/indexer/adapter.php) [function.require-once]: failed to open stream: No such file or directory in /home/twodice1/twodiceboxing.com/plugins/finder/k2/k2.php on line 15

Fatal error: require_once() [function.require]: Failed opening required '/home/twodice1/twodiceboxing.com/administrator/components/com_finder/helpers/indexer/adapter.php' (include_path='.:/usr/local/lib/php:/usr/local/php5/lib/pear') in /home/twodice1/twodiceboxing.com/plugins/finder/k2/k2.php on line 15