i don't know much about version of the lucene system but there may be a resolution for this issue out there.

[Wed Oct 27 11:41:21 2010] [error] [client 192.168.100.27] PHP Notice: Uninitialized string offset: 117 in /home/aparup/mcode/m20/dev1/moodle/search/Zend/Search/Lucene/Index/DictionaryLoader.php on line 230, referer: http://aparup.moodle.local/m20/dev1/moodle/search/query.php?query_string=yellow1
[Wed Oct 27 11:41:21 2010] [error] [client 192.168.100.27] PHP Stack trace:, referer: http://aparup.moodle.local/m20/dev1/moodle/search/query.php?query_string=yellow1
[Wed Oct 27 11:41:21 2010] [error] [client 192.168.100.27] PHP 1.

() /home/aparup/mcode/m20/dev1/moodle/search/query.php:0, referer: http://aparup.moodle.local/m20/dev1/moodle/search/query.php?query_string=yellow1
[Wed Oct 27 11:41:21 2010] [error] [client 192.168.100.27] PHP 2. SearchQuery->__construct() /home/aparup/mcode/m20/dev1/moodle/search/query.php:159, referer: http://aparup.moodle.local/m20/dev1/moodle/search/query.php?query_string=yellow1
[Wed Oct 27 11:41:21 2010] [error] [client 192.168.100.27] PHP 3. SearchQuery->set_query() /home/aparup/mcode/m20/dev1/moodle/search/querylib.php:180, referer: http://aparup.moodle.local/m20/dev1/moodle/search/query.php?query_string=yellow1
[Wed Oct 27 11:41:21 2010] [error] [client 192.168.100.27] PHP 4. SearchQuery->get_results() /home/aparup/mcode/m20/dev1/moodle/search/querylib.php:201, referer: http://aparup.moodle.local/m20/dev1/moodle/search/query.php?query_string=yellow1
[Wed Oct 27 11:41:21 2010] [error] [client 192.168.100.27] PHP 5. SearchQuery->process_results() /home/aparup/mcode/m20/dev1/moodle/search/querylib.php:318, referer: http://aparup.moodle.local/m20/dev1/moodle/search/query.php?query_string=yellow1
[Wed Oct 27 11:41:21 2010] [error] [client 192.168.100.27] PHP 6. Zend_Search_Lucene->find() /home/aparup/mcode/m20/dev1/moodle/search/querylib.php:234, referer: http://aparup.moodle.local/m20/dev1/moodle/search/query.php?query_string=yellow1
[Wed Oct 27 11:41:21 2010] [error] [client 192.168.100.27] PHP 7. Zend_Search_Lucene_Search_Query_Boolean->optimize() /home/aparup/mcode/m20/dev1/moodle/search/Zend/Search/Lucene.php:792, referer: http://aparup.moodle.local/m20/dev1/moodle/search/query.php?query_string=yellow1
[Wed Oct 27 11:41:21 2010] [error] [client 192.168.100.27] PHP 8. Zend_Search_Lucene_Search_Query_MultiTerm->optimize() /home/aparup/mcode/m20/dev1/moodle/search/Zend/Search/Lucene/Search/Query/Boolean.php:165, referer: http://aparup.moodle.local/m20/dev1/moodle/search/query.php?query_string=yellow1
[Wed Oct 27 11:41:21 2010] [error] [client 192.168.100.27] PHP 9. Zend_Search_Lucene->hasTerm() /home/aparup/mcode/m20/dev1/moodle/search/Zend/Search/Lucene/Search/Query/MultiTerm.php:204, referer: http://aparup.moodle.local/m20/dev1/moodle/search/query.php?query_string=yellow1
[Wed Oct 27 11:41:21 2010] [error] [client 192.168.100.27] PHP 10. Zend_Search_Lucene_Index_SegmentInfo->getTermInfo() /home/aparup/mcode/m20/dev1/moodle/search/Zend/Search/Lucene.php:999, referer: http://aparup.moodle.local/m20/dev1/moodle/search/query.php?query_string=yellow1
[Wed Oct 27 11:41:21 2010] [error] [client 192.168.100.27] PHP 11. Zend_Search_Lucene_Index_SegmentInfo->_loadDictionaryIndex() /home/aparup/mcode/m20/dev1/moodle/search/Zend/Search/Lucene/Index/SegmentInfo.php:600, referer: http://aparup.moodle.local/m20/dev1/moodle/search/query.php?query_string=yellow1
[Wed Oct 27 11:41:21 2010] [error] [client 192.168.100.27] PHP 12. Zend_Search_Lucene_Index_DictionaryLoader::load() /home/aparup/mcode/m20/dev1/moodle/search/Zend/Search/Lucene/Index/SegmentInfo.php:572, referer: http://aparup.moodle.local/m20/dev1/moodle/search/query.php?query_string=yellow1