Quickview images too dark.

This is an odd fault but someone might have the answer. When I batch a set of images as 'quickproofs' any files loaded from CF card appear far too dark and it seems the the data is distributed in the bottom half of the histogram almost exactly. Processing tethered captures in the same folder is no problem. I'm using two Macs; a G4 Powerbook and a G4 dual processor desktop machine with the same spurious results.

Is it me?

Damien.