System Environments:
Kernel: 2.6.23.1
Drm: 2.3.0
Mesa: 7.0.2-rc1
Xf86-video-intel: 2.1.99(2.2 pre-release)
Xserver: 1.4

Bug Descrption:
Two startx(using command:startx -- :n) servers can't coexist:the first one can start as normal,then you start the second one,the screen blink several seconds without any output,then go back to console and display following error messages:
(==) Log file: "/opt/X11R7/var/log/Xorg.2.log", Time: Tue Nov 13 08:38:12 2007
(==) Using config file: "/etc/X11/xorg.conf"
(WW) intel: No matching Device section for instance (BusID PCI:0:2:1) found
(II) Module "ddc" already built-in
(II) Module "i2c" already built-in
(II) Module "ramdac" already built-in
(EE) [drm] Could not set DRM device bus ID.
(EE) intel(0): [dri] DRIScreenInit failed. Disabling DRI.
(EE) intel(0): Couldn't allocate video memory

Fatal server error:
AddScreen/ScreenInit failed for driver 0

XIO:  fatal IO error 104 (Connection reset by peer) on X server ":2.0"
      after 0 requests (0 known processed) with 0 events remaining.

at this time,the first xserver still exist and work as normal.

Reproduce steps:
1 startx -- :1
2 startx -- :2