Thsi one is really strange! Occurs on two different computers, one is an
HP laptop running Vista ultimate, and the other a desktop with win7 32 prof.
Both systems have multicore processors, one Intel (two core), the other
AMD 965(four core).
The Phenom II desktop has dual ATI HD5770 video cards in crossfire. The
laptop HP9650, has a single fairly decent but not great Nvidia GPU.

Anyway both will occasionally have a very short display "blink". Under
"normal" conditions, other than wondering why, there seem to be no other
indications or symptoms.

"Old" Solitare was transferred to both machines from XP.
Other that the problem I'm about to describe, no other difficulties seem
to exist.

If the "blip" occurs while dragging & dropping a card the card may be
duplicated! One is on the original card pile, and the other on the new
location/pile. An undo will restore to just one card in the orginal
location! Or, you can continue to play with two identical cards!

Both systems do have AVG active. Anybody else noticed this sort of behavior?
???