After deleting all deletable Win 7 system restore points, opening Win 7 System Restore shows just the latest restore point, which of course cannot be deleted:

But when I tickmark "show more restore points" -- I see a bunch of really old "system image restore points":

Clicking any of these old restore points, I simply get an error message saying they could not be found, and to select another restore point instead. Can someone tell me (1) how these restore points come about -- that they show up only upon ticking the "show more restore points" box and (2) how to get rid of them? Thanks.
