Thanks Harry (#2). How do I boot the DVD with the memtest option, and how do I
run Memtest86, thanks.

I appreciate your comment about bit rot* on the DVD. (*I asume this refers to
deterioration of the physical DVD). I can't discount that possibility (I burned
the DVD about 5 years ago).

But I originally got that Desktop Panel flicker thing (when clicking on the
KMenu icon) within about a year of creating the DVD.

I'm fairly sure I did the md5 checksum on the iso I originally downloaded, and
it was good. I can't remember if I burned the DVD at slow speed, but I don't
think I would have selected a high speed.

I have had the Acer laptop about 5 or 6 years, but my gut feeling is that the
Pioneer DVD drive is reading OK.