textual artifacts

[ross@rosslaird.info (Ross A. Laird)]

I am using the emacs-snapshot package, which, according to the About
screen, is this:

GNU Emacs 23.0.60.1 (i486-pc-linux-gnu, GTK+ Version 2.14.3)

In org-mode (and elsewhere, at times) various bits of text can become
invisible but re-appear when I move the cursor over them. Also,
sometimes when I move about in a file, bits of the file from farther
down (or farther up) will remain displayed in the buffer even though
they are much later or earlier in the document than the current
viewpoint. This is all a bit hard to describe, but it's basically a
situation where textual artifacts keep showing up. And it's not limited
to org-mode buffers, either; sometimes, it happens in the minibuffer
(though mostly, the item just becomes invisible).

Ideas?

Thanks in advance.

Ross