Disappearing property palette objects

[David Epstein]

Using MC 2.5 on Mac 10.4, I've started experiencing the following
glitch, which is new to me:
When I double-click on a group, the group's property palette appears.
But as soon as I click on something on that palette--e.g., the edit
button, or the name tab, or anything--the palette becomes blank (the
header bar is still there, but the window is white).  Less frequently,
the palette shows up blank when the double-click on the group opens
it, but the more usual behavior is that the palette looks fine but
then goes blank when I try to use it.

Anybody else experience this, or have a remedy?

Many thanks.

David Epstein