Ingo Juergensmann: Debian Unstable - nomen est omen

Oh well... in the last days my machine crashed during the nightly backup. When I restarted it the next morning I
realized two problems: the LVM is not recognized anymore and my X crashes on startup.
With the help of Tino Keitel (scorpi) I fixed the first issue by installing an older version of the lvm2 package
(namely: lvm2_2.02.39-7_i386.deb) and libdevmapper1.02.1 (namely: libdevmapper1.02.1_1.02.37-1_i386.deb). Tino reported
this in Bug #546817.

But there's still the Xorg problem left. Xorg.0.log reports:

CODE:(II) RADEON(0): RADEONRestoreMemMapRegisters() :
(II) RADEON(0):   MC_FB_LOCATION   : 0xefffe800 0xefffe800
(II) RADEON(0):   MC_AGP_LOCATION  : 0xf87ff800
restore common
restore crtc1
restore pll1
finished PLL1
set RMX
set FP1
enable FP1
disable primary dac
disable TV
(II) RADEON(0): RandR 1.2 enabled, ignore the following RandR disabled message.

Backtrace:
0: X(xorg_backtrace+0x3b) [0x81314bb]
1: X(xf86SigHandler+0x51) [0x80c57d1]
2: [0xb7f32400]
3: X(xf86DiDGAInit+0x2f) [0x80f08cf]
4: X(xf86CrtcScreenInit+0x110) [0x80ed9e0]
5: /usr/lib/xorg/modules/drivers//radeon_drv.so [0xb7a2a114]
6: X(AddScreen+0x19d) [0x80712cd]
7: X(InitOutput+0x206) [0x80adfa6]
8: X(main+0x1db) [0x80719bb]
9: /lib/i686/cmov/libc.so.6(__libc_start_main+0xe5) [0xb7bb37a5]
10: X [0x8071051]

Fatal server error:
Caught signal 11.  Server aborting

Maybe this is Bug #546586?
I've already detached the second display, but it still crashes. Pointers and solutions appreciated!