Thanks to those who responded, and in particular to Christian Henz. I had not seen this before (from Paul Davies): "The implementation of DRI by certain video interface drivers means that we end up trying to lock the video memory as well, and this tends to fail for various reasons." Uh-huh. Well, that certainly explains what I'm seeing, and it's more than just " *trying* to lock the video memory;" it's quite successful at doing that. The X xerver gets hosed. Regards, Dave.
