Sitecore 6: Problem rebuiling Crawler Index

Problem:

Job started: RebuildSearchIndex|System.Threading.LockRecursionException:
   Recursive read lock acquisitions not allowed in this mode.
   at System.Threading.ReaderWriterLockSlim.TryEnterReadLockCore(Int32 millisecondsTimeout)
   at System.Threading.ReaderWriterLockSlim.TryEnterReadLock(Int32 millisecondsTimeout)
   at Sitecore.Search.IndexDeleteContext..ctor(ILuceneIndex index)
   at Sitecore.Search.Crawlers.DatabaseCrawler.DeleteVersion(Item version)
   at Sitecore.Search.Crawlers.DatabaseCrawler.AddItem(Item item, IndexUpdateContext context)
   at Sitecore.Search.Crawlers.DatabaseCrawler.AddTree(Item root, IndexUpdateContext context)
   at Sitecore.Search.Crawlers.DatabaseCrawler.AddTree(Item root, IndexUpdateContext context)
   at Sitecore.Search.Crawlers.DatabaseCrawler.AddTree(Item root, IndexUpdateContext context)
   at Sitecore.Search.Crawlers.DatabaseCrawler.AddTree(Item root, IndexUpdateContext context)
   at Sitecore.Search.Crawlers.DatabaseCrawler.AddTree(Item root, IndexUpdateContext context)
   at Sitecore.Search.Crawlers.DatabaseCrawler.AddTree(Item root, IndexUpdateContext context)
   at Sitecore.Search.Crawlers.DatabaseCrawler.AddTree(Item root, IndexUpdateContext context)
   at Sitecore.Search.Index.Rebuild()
   at Sitecore.Shell.Applications.Search.RebuildSearchIndex.RebuildSearchIndexForm.Builder.Build()|Job ended: RebuildSearchIndex (units processed: 214)
 

Solution:

Well in my case I just did a stupid mistake. We were trying to delete a Version of an Item that does not exist. So check you Code / Config where you are running custom Code for the Search / Crawling adn Indexing. May you doing stuff with Items that you may not should do.