Dreaded dark buckets with DR

[tricky]

Things have been going OK with a large scene that includes some 30 XREF files. Recently, I have got a problem where my local machines' buckets are rendering darker than all the other render machines. The textures are there, its just that the buckets are darker.

This problem seems to be reasonably common, but I can't for the life of me work out what needs to be checked. Any suggestions?

[tricky]

OK - seem to have solved it...for the moment! It was one of either two things: 1) I reset the irradience mapping and 2) I found a few disabled XREFs within some of the XREFs I was using and got rid of them.