Unfortunately, as we age, our cornea loses flexibility, and we begin to need to hold objects further away from us to be able to focus on them (Presbyopia). This means for some of us, holding it 6"-8" will not be an answer. GIJP may already be feeling these effects.

Also, the shimmering effect may be a sensitivity to the slightly different images each eye gets from the screen. This is caused by both glare effecting the image, but also from the inherently not quite perfect viewing angles of the screen. I found it disturbing at first, but I was able to get over it. On my Toshiba M200 tablet, it was such an issue that I never got over it and had to stop using the tablet. My experience with other M200 owners showed me that there is a very dramatic range in sensitivty to this issue, with some people not noticing it, and others, like myself, being severely impacted.

Then again, the responsiveness issue does sound like a hardware problem with the N800.