An error occurred while attaching module (Dynamicweb.Frontend.Content)

System.NullReferenceException: Object reference not set to an instance of an object.
   at Lucene.Net.Index.SegmentTermDocs..ctor(SegmentReader parent) in d:\Lucene.Net\FullRepo\trunk\src\core\Index\SegmentTermDocs.cs:line 59
   at Lucene.Net.Index.SegmentReader.TermDocs() in d:\Lucene.Net\FullRepo\trunk\src\core\Index\SegmentReader.cs:line 1219
   at Lucene.Net.Search.MultiTermQueryWrapperFilter`1.GetDocIdSet(IndexReader reader) in d:\Lucene.Net\FullRepo\trunk\src\core\Search\MultiTermQueryWrapperFilter.cs:line 118
   at Lucene.Net.Search.ConstantScoreQuery.ConstantScorer..ctor(ConstantScoreQuery enclosingInstance, Similarity similarity, IndexReader reader, Weight w) in d:\Lucene.Net\FullRepo\trunk\src\core\Search\ConstantScoreQuery.cs:line 158
   at Lucene.Net.Search.ConstantScoreQuery.ConstantWeight.Scorer(IndexReader reader, Boolean scoreDocsInOrder, Boolean topScorer) in d:\Lucene.Net\FullRepo\trunk\src\core\Search\ConstantScoreQuery.cs:line 105
   at Lucene.Net.Search.BooleanQuery.BooleanWeight.Scorer(IndexReader reader, Boolean scoreDocsInOrder, Boolean topScorer) in d:\Lucene.Net\FullRepo\trunk\src\core\Search\BooleanQuery.cs:line 377
   at Lucene.Net.Search.BooleanQuery.BooleanWeight.Scorer(IndexReader reader, Boolean scoreDocsInOrder, Boolean topScorer) in d:\Lucene.Net\FullRepo\trunk\src\core\Search\BooleanQuery.cs:line 377
   at Lucene.Net.Search.BooleanQuery.BooleanWeight.Scorer(IndexReader reader, Boolean scoreDocsInOrder, Boolean topScorer) in d:\Lucene.Net\FullRepo\trunk\src\core\Search\BooleanQuery.cs:line 377
   at Lucene.Net.Search.IndexSearcher.SearchWithFilter(IndexReader reader, Weight weight, Filter filter, Collector collector) in d:\Lucene.Net\FullRepo\trunk\src\core\Search\IndexSearcher.cs:line 248
   at Lucene.Net.Search.IndexSearcher.Search(Weight weight, Filter filter, Collector collector) in d:\Lucene.Net\FullRepo\trunk\src\core\Search\IndexSearcher.cs:line 238
   at Lucene.Net.Search.IndexSearcher.Search(Weight weight, Filter filter, Int32 nDocs, Sort sort, Boolean fillFields) in d:\Lucene.Net\FullRepo\trunk\src\core\Search\IndexSearcher.cs:line 212
   at Lucene.Net.Search.IndexSearcher.Search(Weight weight, Filter filter, Int32 nDocs, Sort sort) in d:\Lucene.Net\FullRepo\trunk\src\core\Search\IndexSearcher.cs:line 194
   at Dynamicweb.Indexing.Lucene.LuceneIndexProvider.SearchInternal(IQuery query, QuerySettings settings)
   at Dynamicweb.Indexing.Querying.QueryService.Query(IQuery query, QuerySettings settings)
   at Dynamicweb.QueryPublisher.Frontend.GetContent()
   at Dynamicweb.Frontend.Content.GetModuleOutput(Paragraph paragraph, PageView pageview)