Hi,
The only thing I can think of that you have a custom colour management setting applied to one image in the queue. Not all versions of Qimage can do this, Studio & Ultimate I think.
There'll be a little paint pot icon in the LH corner of the particular print in the queue both on the page preview and the full page editor if a custom profile is set (different from the general setting). See attached to see what I mean..
Terry.
PS. This would have been better in the Qimage section, for future reference