Okay; I spoke with a wonderful Sony rep, Raquel, who had a really, really sexy voice and who did her job extremely well. She consulted her service manual and asked me to do a few things to the set, some of which I had already tried but one I had not. I am a newbie so I might not be accurate on this and please don't flame Sony if what she said is wrong, but she instructed me to change my advanced video setting to interlaced on 1080i sources. I tried this and it did help. If I look hard enough on the gray display box I can still see traces of the issue, but once the display goes away, so far, I cannot see the white line anymore. As soon as I say this, of course, it will come back, but for now I am at least a little happy.
I am comforted by her renewed commitment on behalf of Sony to help with with this and any other problem I might encounter. From what she said, interlaced keeps the 1080i source in it's native mode; progressive and cinemotion up-convert it when none is necessary; obviously 720p doesn't need any help since the issue is not there (ABC, by the way, currently uses 720p which is why the PQ looks fine on ABC while not great on 1080i sources). Makes sense and it works, at least initially. I'll watch a bit tonight and if it's still there I'll call the Sony authorized warranty dealer that Raquel told me about in my area.
I have been able to tweak the HD image and it now is close to being as good as it was on my previous set, although I may just be getting used to great images...perhaps that "wow" factor subsides after a while. So relax, enjoy and report any problems to Sony. The number is in your manual at the beginning of the troubleshooting section.
Nothing is ever going to be perfect and it's only because we spent so much money that we are being a bit obsessive about it all...speaking for myself anyway. Think of your car or house on which so much more was spent and remember the little problems there. We didn't pay the mega thousands required for truly great home theater systems but even there I bet there are problems; heck, in the movie theater last week I was disappointed in the PQ and thought to myself that direct-view was even better than that (real grainy). Do this, go watch TV for a while on your old set. My Samsung which I thought was great at the time I bought it has several glaring problems, not the least of which is very noticable markings on a dark screen and wavy lines which were very noticable on DVDs. I love my XBR and despite the white line and a few other "minor" issues, it's so much better that what I had. Of course it will be better if the white line is truly gone, but if not, I'll pester Sony until they make it right! Hoowah!