I had a corrupted Berkeley database (trackback, comments and log tables) probably due to excessive spamming and because I exceeded my quota on the web host.

The symptoms were: could not list comments / trackbacks or activity log ("no comments found"), and when a user added a comment to a post, it would delete all the other comments and not post the new one.
also, my sys admin complained that some "mt-feed.cgi" was causing 100% CPU load on the server, which was probably due to the fact that periodic tasks didn't finish any more in the alotted time frame (5 mins).

Because the corruption had taken place months earlier (I could still post new entries, so I didn't notice/care), just retrieving the backup wouldn't have been very good.

But I managed to extract the files (and convert to SQLite) in the end. More details here:

http://www.davids-world.com/archives/2007/...ers_deligh.html