> use test
> db.users.insert(

)
> db.getCollectionNames()
[ "system.indexes", "users" ]
> db.system.indexes.ensureIndex(

)
Fri Jun 11 17:39:21 MessagingPort recv() errno:104 Connection reset by peer 127.0.0.1:27017
Fri Jun 11 17:39:21 query failed : xrfang.$cmd

to: 127.0.0.1
Fri Jun 11 17:39:21 JS Error: Error: error doing query: failed (anon):1284
Fri Jun 11 17:39:21 trying reconnect to 127.0.0.1
Fri Jun 11 17:39:21 reconnect 127.0.0.1 ok
Fri Jun 11 17:39:21 query failed : xrfang.$cmd

to: 127.0.0.1
Fri Jun 11 17:39:21 JS Error: Error: error doing query: failed (anon):1284

In the above session I incorrectly called the ensureIndex on "system.Indexes" collection, and crashed the server. if I restart the server and try to do the same thing on the same collection, this bug disappear. But if I created a new db, do the same thing, it still crashes server.