1.2.5pre4: intermittant illumination bug?

[selden]

Sometimes when I use the following sequence of commands to view the moon, the whole model becomes fully illuminated. The dark side is lit. The rest of the time, the visible side is in shasow, as it should be.

Start celestia v1.2.5pre4 (with verbose HUD display enabled, current date)
Press the "Return" key, the "Tatget name" prompt appears.
type in "moon" followed by the Return key
Type the "C" key, viowpoint turns in the direction of the moon
Type the "G" key, viewpoint goes to the moon
Type the "Y" key, "Sync Orbit Moon" appers at lower right
Sometimes the moon (incorrectly) becomes brightly lit when the "Y" is pressed. Sometimes it doesn't.

System: 500MHz P3, WinXP sp1, Nvidia GeForce4 Ti4200, Detonator 40.71 drivers.

Here's a thumbnail of an image capture: