SiS driver won't start X on 12.10

[Thufir]

Ubuntu 12.04 on sda boots fine with the SiS driver and runs LXFCE fine.

Ubuntu 12.10 on sdb boots fine, but no X program will start. Switching to the VESA driver allows XFCE to run on, otherwise the graphical interface will simply flicker:

thufir@dur:~$
thufir@dur:~$ cat /etc/X11/xorg.conf
Section "Device"
 Identifier "Configured Video Device"
 Driver "vesa"
EndSection

Section "Monitor"
 Identifier "Configured Monitor"
EndSection

Section "Screen"
 Identifier "Default Screen"
 Monitor "Configured Monitor"
 Device "Configured Video Device"
EndSection
thufir@dur:~$

The hardware:

thufir@dur:~$ lspci
00:00.0 Host bridge: Silicon Integrated Systems [SiS] 661FX/M661FX/M661MX Host (rev 11)
00:01.0 PCI bridge: Silicon Integrated Systems [SiS] AGP Port (virtual PCI-to-PCI bridge)
00:02.0 ISA bridge: Silicon Integrated Systems [SiS] SiS964 [MuTIOL Media IO] LPC Controller (rev 36)
00:02.5 IDE interface: Silicon Integrated Systems [SiS] 5513 IDE Controller (rev 01)
00:02.7 Multimedia audio controller: Silicon Integrated Systems [SiS] SiS7012 AC'97 Sound Controller (rev a0)
00:03.0 USB controller: Silicon Integrated Systems [SiS] USB 1.1 Controller (rev 0f)
00:03.1 USB controller: Silicon Integrated Systems [SiS] USB 1.1 Controller (rev 0f)
00:03.2 USB controller: Silicon Integrated Systems [SiS] USB 1.1 Controller (rev 0f)
00:03.3 USB controller: Silicon Integrated Systems [SiS] USB 2.0 Controller
00:04.0 Ethernet controller: Silicon Integrated Systems [SiS] SiS900 PCI Fast Ethernet (rev 91)
00:05.0 IDE interface: Silicon Integrated Systems [SiS] RAID bus controller 180 SATA/PATA [SiS] (rev 01)
00:09.0 Ethernet controller: D-Link System Inc RTL8139 Ethernet (rev 10)
01:00.0 VGA compatible controller: Silicon Integrated Systems [SiS] 661/741/760 PCI/AGP or 662/761Gx PCIE VGA Display Adapter
thufir@dur:~$

and OS version:

thufir@dur:~$
thufir@dur:~$ uname -a
Linux dur 3.5.0-21-generic #32-Ubuntu SMP Tue Dec 11 18:52:46 UTC 2012 i686 i686 i686 GNU/Linux
thufir@dur:~$
thufir@dur:~$ cat /etc/lsb-release
DISTRIB_ID=Ubuntu
DISTRIB_RELEASE=12.10
DISTRIB_CODENAME=quantal
DISTRIB_DESCRIPTION="Ubuntu 12.10"
thufir@dur:~$

Apparently, the problem is that X11 changed between 12.04 and 12.10?