Here first some SW- and HW-Details:

SW:
Kubuntu 8.10 Intrepid x64
Kernel: 2.6.27-9-generic
FGLRX-Version: 8.56.4
Catalyst Version: 8.53
OpenGL-Version: 1.4 (2.1.8304 Release)
I first installed the version from restricted manager / jockey and then updated the
actual Catalyst 8.12 driver from the ATI/AMD driver website

HW:
Acer Aspire 5024 WLMi
ATI Mobility Radeon X700 128 MB (PCIE)

The problem is, when i put an external monitor (e.g. CRT) on the external
VGA-connector or a TV Screen on the S-Video-Output and start Xorg in
"Clone-Mode" everything is fine.
I got some problems with the video-overlay. I play a video in the e.g. vlc-window
and I set the ''Option ' ' OverlayOnCRTC2" "1 ' ' , but there is no fullscreen overlay.
But thats another problem I think, also it's related to amdxmm.so

So the problem occurs when I configure the second monitor or TV-Screen as
an independent desktop (Dual-Head) with and/or without Xinerama or BigDesktop.

I tried a all combinations of many Options and there values in xorg.conf.
I think I can't influence these behaviour by the xorg.conf.

Remember: Clone mode works!

When I move "/usr/lib/xorg/modules/amdxmm.so" to another directory or
deleting it, Xorg starts normal with the Dual-Head-Configuration.

BUT: When I delete "amdxmm.so" XVideo is not longer active.
I think it is possibly the interface between XVideo and fglrx???

My Xorg.0.log:
Code:
...
(II) fglrx(0): Acceleration enabled
(II) LoadModule: "amdxmm"

(II) Loading /usr/lib/xorg/modules//amdxmm.so
(II) Module amdxmm: vendor="X.Org Foundation"
	compiled for 1.4.99.906, module version = 1.0.0
	ABI class: X.Org Server Extension, version 1.1

Backtrace:
0: /usr/bin/X(xf86SigHandler+0x65) [0x480f35]
1: /lib/libc.so.6 [0x7fa854c04060]
2: /usr/lib/xorg/modules//amdxmm.so(amdxmmDalHelperGetControllerInfo+0x2b8) [0x7fa8512b6378]
3: /usr/lib/xorg/modules//amdxmm.so(amdxmmInit+0x254) [0x7fa8512b4de4]
4: /usr/lib/xorg/modules/drivers//fglrx_drv.so [0x7fa8537a4186]
5: /usr/lib/xorg/modules/drivers//fglrx_drv.so(atiddxScreenInit+0x6f9) [0x7fa85379c349]
6: /usr/bin/X(AddScreen+0x1c9) [0x432d89]
7: /usr/bin/X(InitOutput+0x241) [0x469a61]
8: /usr/bin/X(main+0x286) [0x433526]
9: /lib/libc.so.6(__libc_start_main+0xe6) [0x7fa854bef466]
10: /usr/bin/X [0x432ad9]
Saw signal 11.  Server aborting.
(II) Screen 0 shares mem & io resources
(II) Screen 1 shares mem & io resources
VG JD.