My widget appears, then disappears
 

This is a very basic question, but I am new to this theme. When I drag a widget into the right side bar, it appears, and I can edit it fine. When I visit the site, it appears in the right sidebar fine also. But whn I go back to edit it, it is no longer listed under the Right Sidebar tab, even though it still appears on the site. Using ATA 3.4.6. thanks.

When you go to the widgets page, if you click on the 'righrsidebar' down arrow, (to expand the view able space, do they show up?

No, they don't. I tried using IE to edit instead of Firefox, and have no problem, so it must be brewser-related. Thanks

Try disabling your plugins and see if it works.