I dunno. Trying to second guess hardware problems, remotely, without pictures, or test equipment, or actual part numbers and datasheets (for the crystals, for instance), or expertise (this is a pretty hard problem, so the amount of test equipment and expertise required could be quite high), is a pretty frustrating experience.
I thought everyone was already using the "full swing driver" fuse 
Of course, I also thought I had already changed in the the Optiboot repository makefiles, and it isn't changed there either! Sigh.