My Xorg crashes after enabling screensaver for some while. This already happens twice when I started xcreensaver [gnome version]. I am running with xf86-video-ati from git head. My system is FreeBSD 7.1-STABLE with Xorg-7.4 (Xorg-server-1.5.3).

The crash log of Xorg says:

---
[many lines as below]
(EE) RADEON(0): ADVANCE_RING without begin at radeon_accel.c:882
[many lines as below]
(EE) RADEON(0): BEGIN_RING without end at radeon_accel.c:859
(EE) RADEON(0): ADVANCE_RING without begin at radeon_accel.c:882
(EE) RADEON(0): BEGIN_RING without end at radeon_accel.c:859
(EE) RADEON(0): BEGIN_RING without end at radeon_accel.c:692
---

It seems these lines caused the problem. But I don't know exactly what it is.