X hang VT switching (radeon R500)

[curaga]

Occasionally doing a VT switch causes X to hog 100% cpu, slowing everything down. At that point I have to do "killall -9 X" to get my comp back, it won't listen to other signals.

This happens maybe every 7th VT switch, randomly. I use the vesa fb on my console.

After this a message is printed on my terminal:

Mutex destroy failure: Device or resource busy

This error does not appear in any of my logs. Also, there are no other errors in the logs either.

Last of Xorg.0.log:

(II) AIGLX: Suspending AIGLX clients for VT switch
Output CRT1 disable success
Blank CRTC 0 success
Disable CRTC 0 success
Blank CRTC 1 success
Disable CRTC 1 success
(II) RADEON(0): RADEONRestoreMemMapRegisters() :
(II) RADEON(0): MC_FB_LOCATION : 0xefffe000 0xefffe000
(II) RADEON(0): MC_AGP_LOCATION : 0x003f0000
(II) RADEON(0): avivo_restore !
Enable CRTC 0 success
Unblank CRTC 0 success

And of dmesg:

Feb 28 11:27:28 Valinor kernel: [drm] Loading R500 Microcode
Feb 28 11:27:28 Valinor kernel: [drm] Num pipes: 1
Feb 28 11:29:14 Valinor kernel: [drm] Num pipes: 1

Xserver 1.5.1, Radeon 6.11.0, Mesa 7.2, X1300 Pro pcie

I won't report this officially yet, as they would only tell to try the latest pieces, which I will when Mesa 7.4 and X 1.6.1 are out. In the meanwhile, any comments?

PS: I seem to be able to cause the same symptoms by crashing OpenArena, ie the 100% cpu usage and the mutex error, 100% repeatable, but I'm not sure if that's another bug.

PS2: Not an Xserver bug, since it did not happen with my Matrox (all other pieces were the same)