Search problem

Hello,

when doing a simple search through the lucene indexes in some mailboxes (with actually many subfolders) the search terminates after a few seconds with no result and the dovecot log shows this error:

Fatal: master: service(imap): child 15433 killed with signal 6 (core not dumped)

Any clue about the reasons? the lucene indexes have been already rebuilt and look OK.

Regards

-federico