[Zope] Index crash in ZCatalog? Anybody recognize this?

[Lennart Regebro]

We have a catalog that we search amongst other things on dates, using code
like this:

query['date'] = DateTime.now()
query['date_usage'] = 'range:min'

This selects all records that have either a date that is lower than "now" or
where this field is empty or None.

Suddenly these queries stopped working on one catalog. The query would no
longer return records with empty or None in the date. If we skipped the
'date_usage' and searched for [DateTime.now(), '', None] then the '' records
would get returned, but otherwise not.

Deleting the catalog, creating a new one and reindexing all objects solved
the problem.

Two questions:
1. I assume that this index crashed. Any other ideas of what could have
happened?
2. Are there any known bugs to crash indexed in Zope 2.3.3 that have been
fixed later? I could find nothing when I searched the archives.