[GeoNetwork-devel] Error changing system settings

I am running a deployment of 2.7.0 at the moment, built from the
source code on trunk. I went to change some of the system settings
(under Administration->System Configuration). When I hit save, even
when there have been no changes made, I get the following error

Unable to save system configuration
NULL not allowed for column SOURCE[90006-104]
JdbcSQLException

Have other people encountered this? Is it a known bug? What should I
do to get around it?

Thanks,

Elgar Storm