Panel flicker

[feardapenguin]

I searched on this issue but didn't come up with anything.

A weird problem cropped up recently with my desktop. I run Metacity with a menu/icon panel at the top of the screen. When I have no open windows on the desktop my panel rapidly flickers in and out intermittently. Looks like static noise with horizontal lines going across the screen region where the panel is located. No other portion of the screen is affected, only the top panel. I run a taskbar panel at the bottom of the screen and it does not behave this way.

Opening a full-screen window causes the panel to return to normal. Half-size windows (or no window at all) brings the flickering back.

Any idea how I might begin troubleshooting this? Has anyone else seen the issue?