TILE MYSTERY
Correct, BOAC: I just want to see all pics as mini-thumbnails as I did previously - and then make a choice. Otherwise I have to open many to find the one I want rather than just glance across the selection.
Avtrician - thanks. I guess BOAC's answer sums it up. Will check Picasa isn't the default . . . but then it'll probably revert to Photoshop Elements. Re the question about what setting I have in View - it's Large Icons but when I changed briefly to Small Icons and Medium Icons it made no difference so I changed back to Large Icons.
Meantime, alas the problem persists!