virtualbox.org

I've been using VirtualBox for a while. All of a sudden (within the past few weeks, at any rate -- today's the first time I've tried in a while), when I click on a particular virtual machine to open it and move my mouse into that machine, the entire host display flashes and goes into what looks like 8-bit mode, making it essentially unreadable. When I move my mouse outside of that machine, the display goes back to normal.

If I then exit VirtualBox and restart it, the same thing happens in the main VirtualBox window.

Any thoughts?

It appears that if I turn off DRI this problem goes away, but needless to say that's not what I really want to do. I have a Radeon X700; this happens with both radeon and radeonhd, with X server 1.6.2.