When a search is submitted we are getting memory errors.

For example:

ERROR WritableIndex 2010-08-10 08:39:08,213 SearchService:index : Indexing error deleting dav:/_webdav/Jim/Savas25Q/@files/mascot/Savas25Q/20060728_HH_590_25Q_NE_repeat_11.pep.xml
java.lang.IllegalStateException: this writer hit an OutOfMemoryError; cannot flush
    at org.apache.lucene.index.IndexWriter.doFlushInternal(IndexWriter.java:3521)
    at org.apache.lucene.index.IndexWriter.doFlush(IndexWriter.java:3509)
    at org.apache.lucene.index.IndexWriter.flush(IndexWriter.java:3500)
    at org.apache.lucene.index.IndexWriter.deleteDocuments(IndexWriter.java:1974)
    at org.labkey.search.model.WritableIndex.deleteDocument(WritableIndex.java:81)
    at org.labkey.search.model.WritableIndex.index(WritableIndex.java:68)
    at org.labkey.search.model.LuceneSearchServiceImpl.index(LuceneSearchServiceImpl.java:724)
    at org.labkey.search.model.AbstractSearchService$7.run(AbstractSearchService.java:978)
    at java.lang.Thread.run(Unknown Source)
ERROR LuceneSearchServiceImpl 2010-08-10 08:39:08,213 SearchService:index : Indexing error with dav:/_webdav/Jim/Savas25Q/@files/mascot/Savas25Q/20060728_HH_590_25Q_NE_repeat_11.pep.xml
java.lang.IllegalStateException: this writer hit an OutOfMemoryError; cannot flush
    at org.apache.lucene.index.IndexWriter.doFlushInternal(IndexWriter.java:3521)
    at org.apache.lucene.index.IndexWriter.doFlush(IndexWriter.java:3509)
    at org.apache.lucene.index.IndexWriter.flush(IndexWriter.java:3500)
    at org.apache.lucene.index.IndexWriter.addDocument(IndexWriter.java:1952)
    at org.apache.lucene.index.IndexWriter.addDocument(IndexWriter.java:1906)
    at org.labkey.search.model.WritableIndex.index(WritableIndex.java:69)
    at org.labkey.search.model.LuceneSearchServiceImpl.index(LuceneSearchServiceImpl.java:724)
    at org.labkey.search.model.AbstractSearchService$7.run(AbstractSearchService.java:978)
    at java.lang.Thread.run(Unknown Source)
ERROR DavCrawler 2010-08-10 08:39:41,933 DavCrawler : Unexpected error
java.lang.OutOfMemoryError: Java heap space
ERROR LuceneSearchServiceImpl 2010-08-10 08:39:52,850 SearchService:index : Indexing error with dav:/_webdav/Jim/Savas25Q/@files/mascot/Savas25Q/20060728_HH_590_25Q_NE_repeat_13.dat
java.lang.OutOfMemoryError: Java heap space

Is there some way to avoid this problem?

thanks

Ron